I was a big believer in Haxe, it seemed perfect. The main issue I and many people had at its inception was that the ecosystem was very fragmented. The promise was "write once, run everywhere" (which is what we had with Flash), but each platform you wanted to actually compile on was a whole process, often undocumented, with lots of caveats, and having to hunt for third party community wrappers to do the native integrations you want etc.
This was ~10 years ago, I'm sure the current state of the ecosystem is very different (no idea), but this is the reason why I was never able to adopt it, and I heard the same thing from dozens of Flash creators at the time.
