I miss flash too. No other development environment was/is as easy to use.

I learning to program with as2 and as3.

If you weren't aware previously, you'll be pleased to learn that you can still program in Flash if you really want to, and distribute your programs on the web. https://ruffle.rs

We need an open source equivalent to the Flash editor (AKA Adobe animate) that uses Ruffle and can output to it.

We have the web, we don't need ruffle, what we need is indeed a open source flash editor. Wick editor was quite close, by outputting standalone html files

https://www.wickeditor.com/

Of course, not at all on the same level like flash was, but some parts worked really nice.

Unfortunately it is abandoned. (I thought about taking it up, but would require lots of effort, basically rewriting core parts)

The web is awful as a programming environment. It's popular because it's everywhere, not because it's good.

Rather a warts-and-all open web than a pay-to-play walled garden where you have to pay the feudal lord a tax for sharecropping on their land.

there are alternatives both in the past (perpetual software) and hopefully in the future

I think they mean you don't need ruffle if you can just export to web. The programming environment can be anything, but adding ruffle in the middle when it really doesn't need to be there, does indeed feel a bit tacky. Flash used to be necessary to add functions to browsers that were otherwise impossible, but these days you can do anything in a browser.