Yep, in fact they seem to be actively opposed to legacy support. You can get a sense of that here:
Yep. I can’t find it now, but I know I’ve read posts on Discourse Meta where they specifically say they don’t want to spend their time doing that or maintaining a hodgepodge of workarounds. So the onus is very much on the user to use a supported browser, which especially in the case of iPhone / iPad users can even mean obtaining a different device that supports Discourse’s required Safari engine version (due to Apple’s weird insistence on forcing even alternative browsers on those platforms to use Apple’s own internal rendering engine). So I don’t agree with the cavalier dismissal of users’ individual circumstances with “just upgrade”, but unfortunately that’s one of the few major downsides that comes along with the many unique advantages of running Discourse.