PCs had a different (open) hardware architecture using chips, chipsets, motherboards and other components from a variety of manufacturers (Intel, AMD, Cyrix, Nvidia (later), etc).
Macs had their own architecture from top to bottom from the Motorola chips (680x0, PowerPC, etc) to even the system interconnects.
This custom hardware slowed down the innovation at Apple and drove up the cost at a time when horsepower was really important.
What killed the Mac was cost and scale so when the final nail in the coffin came with Windows 95 (which exceeded the technical capabilities of MacOS in about every way, UI sensibilities notwithstanding) the disparity was vast.
Now? The upper bound on power isn't cost or availability, it's something far more immovable: battery life, size and weight. All the while, CPU differences are largely nonexistent (Snapdragon, Apple's A4/A5, etc).
So, to be clear, you could buy a better (specced) PC for less money than a Mac. Now you can buy a worse Android phone for less money. There's obviously a market for low cost handsets but I don't think anyone can argue that any Android hardware is significantly better than Apple hardware in any way that consumers actually care about.
You see this in, say, the TV market too. If the cheaper but worse hardware argument held then Chinese TVs would kill off higher quality brands. I once heard there are three tiers of TVs: Japanese (top), Korean (middle) and Chinese (bottom).
Chinese TVs are obviously a big market but they aren't the entire market. Nor are Samsung (Korean), Sony or Panasonic going anywhere anytime soon.
Don't you think, that initially, the Mac had a performance advantage because it was integrated? i.e. The hardware details, OS, software was all carefully designed to give snappy performance, despite low specs.
But this lead didn't last long, and the picture you describe came about within a few years.
For Android/iPhone: as soon as the separate components become the source of performance (speed, battery life), rather than the intricate integration of them (SoC design, battery, display, OS, apps, appstore, toolchain, etc), then Android will win.
e.g. Currently, an Android with a faster processor is less snappy than an iPhone. But when processors are fast enough, the difference won't be noticeable - even if the iPhone is still faster.
My prediction is that if Apple can keep finding improvements that users care about (e.g. slimness, lightness etc) that offset gains in component performance, and benefit from how exactly it is all integrated, then it will retain leadership. I also think that this lead cannot last forever.
Apple doesn't expect it to - they'll be on to the next cool thing, where the benefits of integration again become crucial (e.g. the next smaller form-factor).
One thing that's different today is that ARM's SoC market itself is vibrant, and so the processor won't stagnate like the 680x0 did - even if Apple's internal team does stagnate, they can just buy another team (like how they got the A5 guys). They can even mix and match different components within the SoC. From what you're saying, this is what makes it different from round one.
As of the iPhone 4 release, you could buy slightly better hardware in a Android phone for the same/less (e.g. Galaxy S, near identical hardware but better GPU and faster clock). Since the release of dual-core Tegra2 phones, Android has had a clear hardware/price advantage over Apple at the top, middle and bottom of the smartphone market. If iPhone 5 is really delayed till fall it's unclear if they'll ever match the top-end phone in hardware terms again.
I don't know if that passes your test of being better "in any way that consumers actually care about", but I will note that they've been collectively outselling Apple for over a year now.
The real thought here, I think, is that adoption drives hardware improvement -- only if you're selling a hojillion chips can you make them cheap, good, and profitable. From this perspective, what you'd want to say is that large market share advantages are extremely defensible and can let you crush the little guys (which apple was through the 90's). But how do you get there in the first place?
The analogy between android/iOS and windows/mac I think has to be well-taken, but most discussions (including this one) leave out the most important difference. Windows got to sell a hojillion units by being the best at selling to business. You buy multi-thousand-dollar machines for all your employees because you expect productivity increases; you don't worry too hard about whether they like the machines or not. The decision maker buys on specs and price if it's not just a salesforce versus salesforce game (a likely win for the open platform because there are more players behind it).
The current generation of mobile, however, is a consumer phenomenon. Businesses aren't buying modern smartphones for their employees -- they're hooking the employees' phones into their networks. Adoption is not driven by purchasing managers but by consumers and therefore by user experience, consumer marketing, branding, etc. in addition to specs and price. This puts the open platform with the worse user experience for the average user at a big disadvantage, particularly if the price differential isn't that large in absolute dollars, which it isn't by comparison with the computers of the 90's (the gap between comparably-specced PC's and mac's being enough to buy multiple smartphones).
I don't know that it makes sense to think of any platform being as strong a winner as windows was; the very presence in the market of a company eager to use an operating system as a loss leader means that android will probably never shrink as small as apple did. However, Apple's advantages in design and branding play to the challenges of the mobile market in a way that they simply didn't for PCs. To this, add the scale advantage Apple currently enjoys (as monopsony buyer of flash memory and LCD's) that locks in big profits that competitors can't touch and it seems quite clear which way the playing field is tilted.
tl;dr: windows won by owning the business market; mobile plays to apple's strengths in a way PC's never have.
PCs had a different (open) hardware architecture using chips, chipsets, motherboards and other components from a variety of manufacturers (Intel, AMD, Cyrix, Nvidia (later), etc).
Macs had their own architecture from top to bottom from the Motorola chips (680x0, PowerPC, etc) to even the system interconnects.
This custom hardware slowed down the innovation at Apple and drove up the cost at a time when horsepower was really important.
What killed the Mac was cost and scale so when the final nail in the coffin came with Windows 95 (which exceeded the technical capabilities of MacOS in about every way, UI sensibilities notwithstanding) the disparity was vast.
Now? The upper bound on power isn't cost or availability, it's something far more immovable: battery life, size and weight. All the while, CPU differences are largely nonexistent (Snapdragon, Apple's A4/A5, etc).
So, to be clear, you could buy a better (specced) PC for less money than a Mac. Now you can buy a worse Android phone for less money. There's obviously a market for low cost handsets but I don't think anyone can argue that any Android hardware is significantly better than Apple hardware in any way that consumers actually care about.
You see this in, say, the TV market too. If the cheaper but worse hardware argument held then Chinese TVs would kill off higher quality brands. I once heard there are three tiers of TVs: Japanese (top), Korean (middle) and Chinese (bottom).
Chinese TVs are obviously a big market but they aren't the entire market. Nor are Samsung (Korean), Sony or Panasonic going anywhere anytime soon.