You're using the web browser wrong.
I don't think this is a legitimate complaint for SoylentNews, but I do believe it is legitimate for other sites.
For example, GitHub and others like them. I prefer to run an older version of FireFox with all my favorite plugins installed, then one day, I went to GitHub and got a nag to upgrade and -- worst of all -- the "download repo" button didn't work. At all.
Now, I can understand more subtle functionality on more complicated structures and components being borked, but having that one simple button do fucking nothing (and other sites that try to flat-out disable all of the website) is just willful malice. Of course, this is Github we're talking about, so their staff are a bunch of fat pink-haired Jews, and Jews of course are annoying for the sake of being annoying. Fortunately, user-agent switchers are a thing.
" B-but muh Git command line! "
When doing research in real time looking for code to s̶t̶e̶a̶l̶ be inspired by, clicking the damn button in the browser is really the quickest way. I just might be pushed into the latest version of Firefox as soon as suitable substitutes for the plugins I like are available and stable -- and no, not just ad and script-blocking shit.
Stupid version checks like this are what drove me to move to PaleMoon and disable sending user agent info.