I think it's far more likely that they've maintained their position through first-mover advantage than anything else. Steam is a website wrapped in an application that was built before building applications out of websites was cool, and it shows -- what you get is an outdated version of WebKit and a video player that somehow manages to be worse than the one Polygon uses, and Steam doesn't even have "monetization" as an excuse there. They've largely abandoned curation, Early Access and Greenlight are a steady stream of horror stories... there's a large list of things wrong with Steam that nobody at Valve seems to even care about fixing.
I don't agree. I think the first-mover advantage gave them a big leg up, but people wouldn't have kept using the platform for 12 years if they were relying entirely on that. Competitors like Origin might have had a fighting chance if Valve hadn't constantly been creating a superior suite of products.
You mention issues with Early Access and Greenlight, but these seem like trivial problems when compared to how solid the platform is overall. Steam as a platform is just far and away superior to any other choice in the gaming space. I can play any PC game at my desk or in my living room. The interface scales great to a TV screen. The Steam Controller is innovative and incredibly customizable, and it's supported by virtually any game in Steam. SteamVR is very fully developed itself and supports both the Rift and the Vive; it even goes so far as to support Chaperone with the Rift despite the Rift not having any room-scale-tracked controllers yet. It has honestly grown into one of the best software ecosystems I've ever seen by offering functionality that competitors can't even dream of.
I hate steam and I rarely use its features outside its store and the friends list. Yet steam remains my primary digital distributor exactly because they got there first.
Later it has basically become impossible to avoid steam, if you want access to every game at least. X-com for instance required steam. Steam is also where all my friends have their profiles.
Even if steam didn't have a monopoly on certain games they still own the access to your library and won't allow you to take it with you.
If you ask me valve is right up there with the worst of them as far as exploiting their monopoly goes.
What has Valve done that's so bad in terms of "exploiting their monopology"? I honestly don't know what you're referring to. They do not even request store exclusivity from developers. If a developer or publisher decided to require Steam, that was their decision, not Valve's.
I guess you could point to Steam's DRM, but it's always had that, long before it was the de facto standard platform and before any monopoly existed.
I think you're talking about a lot of features here that don't even amount to a percentage point of Steam users. Go look at the Steam Hardware and Software Survey results. SteamOS doesn't even show up in the top five Linux distros that Valve reports. There may be Windows users who are using the Big Picture Mode, but I'd guess not a whole lot of them. There may be Windows users who are using the Steam Controller, but I'd guess it's smaller than the ones using Big Picture Mode. Those are not the reasons Steam is beating Origin.
Valve doesn't publish figures on the number of Steam Links sold. But just look at the Steam Hardware Survey[1]. Valve recommends a quad-core PC to be used as the host[2]. But half of Windows users have two CPUs or fewer. The number jumps up to 64% when you look at OS X users. Meanwhile, the top 10 graphics cards are pretty well split betweel the latest NVIDIA cards and a bunch of Intel on-motherboard cards. I don't think the sort of enthusiast that buys a Steam Link is anywhere close to the bulk of Steam's audience; there are a lot of people who are playing games on laptops, not gaming laptops but just laptops.
I still find it very implausible that first mover advantage alone made Valve into a sustainable multibillion dollar company for so long with very little lock-in and very few anticonsumer practices. They have consistently outmaneuvered all their competitors for over a decade on multiple fronts. Their foray into hardware is just the most recent example. I think pointing to an outdated version of WebKit contained in the app is really grasping at straws for trying to find a way to make it look bad.