Simple: it's because not solving this problem is how our godawful industry makes most of its money. Empowering the user means relinquishing control over their "journey"[0]. Ergonomics means fewer opportunities to upsell or show ads.

I don't have the link handy, but I'm reminded of one of the earliest Windows user interface guidelines documents, back from Windows 95/98 era, which, in a section about theming/visual style, already recognized that they have to allow for full flexibility, because vendors will insist on fucking the experience up for the sake of branding anyway, and resisting it is futile[1].

--

[0] - I'm trying really hard to hold back my contempt towards terms like this, and the whole salesy way of viewing human-computer interactions.

[1] - They put it in much more polite terms, but the feeling of helplessness was already there.