As a flash consumer from 2001-2011 I must tell you that honestly; flash was fucking painful.
Run a very weird binary blob riddled with security holes and questionable browser integrations or suffer.
Yes, some things became possible (habbo hotel, flash games, video/audio before browsers supported it) but it wasn’t worth it. I very much wanted flash to die by 2006 and ran a lot of extensions to bypass flash on Linux such as the “HTML5 everywhere” browser add on that tried to force YouTube to use HTML5 video (with mixed results).
I think anyone looking at flash now is romanticising the past. It was the least enjoyable thing about web browsing in the 00-s