I know websites don't work like phones, but on the os slowdown on older phone thing, sometimes that is a thing that needs to be done as newer code can be "interesting" on older things and can cause minor inconveniences like more rapid battery drain or small explosions. When I had my webdev business we only supported major browsers two versions down from the latest which involved writing nice scss for the latest browsers with the nice technology, then detecting for older browsers and in the case of IE which I still hate and am glad it's dead devolving into a horrendous spaghetti mess. And that was just for a stupid website on stupider browsers, would hate to think what they need to do with hardware XD
Anyway yes, trying to maintain really old stuff on top of trying to keep up with/develop for new stuff is seriously exhausting in and of itself and then you have to deal with the people who can't/won't upgrade constantly whining about how it's all a huge conspiracy to force them to spend even more of their hard-earned money and you're a terrible, selfish, greedy person/company for not ensuring they are looked after indefinitely.
I may or may not still secretly harbour somewhat bitter feelings towards a person I don't even remember what they look like never mind their name who was angry about a website not displaying properly in IE5 or something like that well past IE5's expiry date
I think what you've just shown (again) is why critical things shouldn't be centrally controlled even if it is a lot more convenient that way XD