>Flash was great. Is there anything Flash could produce that wouldn't render these days with SVG + CSS + JS?

This has more or less been the line from the day Steve Jobs decided Flash would never be available on the iPhone. And it was readily apparent that no one who said that worked in the audio domain. Things are much, much better now, but I remember challenging myself by trying to build a drum machine in HTML, Javascript, and CSS (not wanting to muck about in Canvas at the time) and while I could make it look decent enough, there was no such thing as a solid, reliable clock in Javascript, for about a decade. Just the way you played audio files back varied from browser to browser on the same machine. It was absolute garbage.

In-browser capabilities have basically caught up or exceeded what Flash did - I don't keep up anymore - but to echo other replies, the authoring tools just aren't as accessible. Maybe vibe coding tools close that gap. But the forced sunsetting of Flash set online interactive multimedia back at least a decade. It was never my main career path, but I more or less abandoned that fun side quest, and as evidenced by my feeling the need to comment here, it still kind of bums me out.