Comment by TeMPOraL
It's worse than that. Accessibility is actually opposite to what the business wants, and the combined cultural and (occasionally) legal backing it has is our last line of defense of user autonomy.
Assistive software is just a different user agent. A non-standard browser interpreting the page in ways different than the vendor intended. The very same feature that enables a screen reader to help a blind person navigate, enables everyone else to identify and snip off ads and upsells, escape the thick sewage that's called "web design", and get straight to the actual thing one came for in the first place. Accessibility is the only thing that prevents the web from becoming Flash again, entirely unparseable through automated means[0].
Again, were it not for cultural and legal insistence to cater for the disabled, we'd all already be completely without agency on the web, dumb riders in a theme park paying for something at every turn. Cutting curbs and such? Why, so the users complete their "journey" faster and leave less money behind?
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[0] - LLMs changed the equation here recently, mostly in our favor, for now. In the immediate term, they can make any website machine-interpretable no matter what the vendor does. But that's just the beginning, we don't yet know how vendors will abuse GenAI to thwart the users.
Web sites hate the idea of a web ecosystem with dozens of (if not thousands of) User Agents, each of them presenting the site in a way the user wants it to be presented. We have strayed so far from the path of HTML being text markup that suggested formatting and semantics only. We have basically handed control over all the content, its presentation, and its interaction modes, to the web developer.
My ideal version of YouTube is a bare HTML page with a single <video> element that the User Agent decides how to interpret and render. And maybe some <li> links to navigate through the site to find other features. Maybe my User Agent is a browser, but maybe it's a video player, or some kind of assistive video display for the disabled. Or a powerpoint slide. Or a command line downloader. As a user, I should have control over how the web content is ultimately rendered, and the only job for the web site is to send me structured content that my renderer can pull apart, understand, and render in the way I see fit.
Similarly, my ideal version of Amazon is a bare HTML page with a search box and a structured list of products and their attributes, that my User Agent can ingest, understand and render in whatever way it sees fit.
Web sites have totally abandoned this path of giving the user control, and now when we GET from a web site, instead of structured, semantic data, we get a big opaque blob of JavaSludge that our browser is expected to faithfully execute as-written, so that the web company gets to make all the major presentation decisions. The user is just the passenger along for the ride.