A button looking like a button isn't an age (of the reader) thing.

Of course it is. What should a button on a screen look like, after all, it has absolutely nothing to do with a large mechanical button from the 80s the old designs tried to emulate. In fact, such buttons are becoming rare even in the physical world, the younger generation is more and more accustomed to touch buttons for operating all kinds of machinery around them. So "like a button" is very much an age thing

Looking like a "touch button" is still looking like a button. Some indication that an element is tappable is still useful.

Game consoles are still pretty popular, I don't think people are going to forget what real buttons are for at least another couple of generations.

Nah, one of the things I found in Discord's accessibility settings is an ability to turn off or reduce animations and other visual effects by default, which is wonderful no matter your ability.

Possibly a factor, but I also think these issues are becoming much more widespread, leaving us less able to tolerate them than when they were less common.

These things are like a sidewalk having a ramp that was originally made for wheelchairs but then suddenly everyone uses it because it’s just a nicer experience with less chance of tripping and falling flat on your face.