It was a path to programming for a lot of artistic minded kids who enjoy learning things on their own. They could start by slowly adding programming to animations until it became a game they could share with their friends. A lot of these people grew up into development jobs. I think if the barrier to learning was picking up ES6 and React or Unity before being able to make a functional game, a lot of them would not have gotten started.

This is not a small thing.

This is why they should open source it if they aren't planning to do anything with it.

They are doing something with it, they renamed it to Animate and made it export to HTML5. They're just killing the format.

Wrong. https://en.wikipedia.org/wiki/List_of_Flash_animated_televis...

Flash is one of the best workflows for animators ever. This is equivalent to Photoshop being EOL'd because Apple doesn't like the pictures you can make with it.