The original promise of client/server services was that the server would provide data on a universal open data format, and the USER AGENT (initially a web browser, but other kinds were expected) would process it in a format to the liking of the user, and satisfying their needs.
Compare this to the current situation where the industry standard is that the servers do indeed provide data through somewhat standardized APIs, but the browser or native app is developed by the same vendor and serves their commercial interests, not those of the user as a customer. The only standard customization recognized to users is light theme / dark theme, and it has only started a few months ago.
The market is not the problem. The misaligned setup of the market, where the interests of the most of the consumers are misaligned with interests of those who produces or pays for the content, is the problem. Imagine a grocery store which is actually a money laundering front for mafia, so it's much more interested in looking like a grocery store than actually selling any groceries. Do you think they'd sell high quality goods? Would they have the best prices? Would their customer service be excellent? Now imagine the mafia bought all (or almost all) grocery stores in town and turned them into money laundering outlets. How is your grocery shopping experience now? That's what we're having with ads.
The reality is that every company wants to have things presented in the same way they're prepared, for the purposes of marketing. That's why web browsers with css are a thing at all - to allow a website to look exactly like what the developer/company behind it wants it to look like.
Why would any company provide data in a standard API so that users can use that data in a standard way? If there was an API for banking, Bank of America wouldn't be able to showcase a professional-esque design and Sofi wouldn't be able to showcase a cartoonish modern design to strengthen their image and attract customers. How do they then attract customers? Only by features and lower margins, which is the opposite of what would make them money.
Remember that the original vision for the web was not made for companies, but for academic or government institutions.
The idea was to have computers support users, not customers. These words have become synonyms but they have quite different implications. The stated goal was to augment the human intellect, for which you need a well organized corpus of knowledge (think Wikipedia, whose spectacular growth and supporting community came from not being a commercial initiative).
But nowadays the whole industry is focused around building products and services that can be packaged and sold, to the point that its professionals can't even think of any other possibilities when discussing the characteristics of the ecosystem.
Incentives are completely different; it's no wonder that interests of industry are misaligned with actual needs of the final users.
The original promise of client/server services was that the server would provide data on a universal open data format, and the USER AGENT (initially a web browser, but other kinds were expected) would process it in a format to the liking of the user, and satisfying their needs.
Compare this to the current situation where the industry standard is that the servers do indeed provide data through somewhat standardized APIs, but the browser or native app is developed by the same vendor and serves their commercial interests, not those of the user as a customer. The only standard customization recognized to users is light theme / dark theme, and it has only started a few months ago.