First, in the US accessibility support is the law. While it is far from well* enforced, your simple formulation of “priorities” obscures the fact that the team is prioritizing convenience vs law. Yes we all do this when deciding, say, how fast to drive. But we know when we are speeding.
Second: in physical space: ramps are required to be implemented in a way that supports wheelchair use. Yet they create alternative affordances: I have appreciated them when when I have broken a limb, for example, even though they weren’t “intended” for that. They are clearly mostly used by delivery people; not only does it make deliveries easier, but reduces incidents of injuries, strains etc.
The same applies to web sites: cleaner affordances allow people to use the page in ways not imagined by the designer.
* By imperfectly I don’t mean “not hyper vigilantly”, I mean that it is often observed in the breach; sometimes it can have negative effects (consider the Berkeley videos case), etc. But that is much better than no attempt at all.
> First, in the US accessibility support is the law
Only for governments or businesses that are open to the public. I've rarely worked on those type of websites. But plenty of B2B stuff. There's a ton of it.
Not your main point, but in the Berkeley videos case I blame, well, Berkeley. They could have taken the videos offline temporarily, worked on transcribing them, and brought them back gradually (they have the resources or, if they’re too cheap, could have resorted to crowdsourcing). Taking that wealth of knowledge offline so abruptly, and with no plan to ever bring it back, is really a disgrace. The videos live on thanks to Archive Team, but they’re not as easy to discover.
Second: in physical space: ramps are required to be implemented in a way that supports wheelchair use. Yet they create alternative affordances: I have appreciated them when when I have broken a limb, for example, even though they weren’t “intended” for that. They are clearly mostly used by delivery people; not only does it make deliveries easier, but reduces incidents of injuries, strains etc.
The same applies to web sites: cleaner affordances allow people to use the page in ways not imagined by the designer.
* By imperfectly I don’t mean “not hyper vigilantly”, I mean that it is often observed in the breach; sometimes it can have negative effects (consider the Berkeley videos case), etc. But that is much better than no attempt at all.