13 years ago I was working on a project for IKEA, a room planner. We used Flash and it was a seriously ambitious project. The level of interactivity that was possible when using Flash was unrivalled for a long time. It appears that most of these type of “sites” has been replaced by native apps, even though the web platform has most of the required capabilities now. Flash was fun to develop with, as everything was well integrated and just worked, and pioneered many of the technologies we now see as part of the web platform APIs. A lot of the criticisms of Flash is due to shitty timeline-based banners which used up the CPU. You could definitively make efficient, fast performing apps/sites using Flash/AS3 if you knew what you were doing. Of course I moved on to JS/TS development, but it isn’t as fun.

The larger issue than stability is that WebGL is an entirely different framework, serving entirely different ends.

For the abstractions Flash supported (objects with behaviors, scenes, timelines), WebGL is way, way too low-level. WebGL is more the kind of thing someone would write Flash on top of.

I think it’s OK to say that work is ongoing in this area.