In which country are you seeing that?

For me the biggest offender are usually Google products and sometimes the lazy-coded website written by incompetents and whose audience is the tech illiterate (i.e. some websites involving schools/teaching) that just tell you "use latest Chrome just to be sure, download here" to, well, just be sure. Notable mentions for government websites that are like 10 years in the past and that are still on the "Supports Firefox" side because, well, they are just always late to everything.

Seems really dumb to let a crappy bank site dictate what browser you use for everything else.