Some of you might remember when a 3mb flash animation could pack in some 5 minutes of animation, with the more advanced ones even having chapter/scene selectors, which could also include clickable easter eggs and other kinds of interactions during the scenes.
We wish the security issues were what killed flash, but it had more than twenty years of security issues failing to kill flash. Flash died because it was replaced by newer technology.
I wouldn’t say it died, I remember years of people calling it dead but it still seemed to have communities up until support was forcibly removed in 2021. I’d say it was killed, in a very “bring out your dead” (“I’m getting better!”) fashion.
Like OP is saying, it wasn’t really* replaced. If vector video was in HTML5 spec to the point you could watch (non-prerastered) vector animations on Youtube (or former Flash sites similar to what Ruffle does, but with less overhead) that would still be abandoning the interactivity but I’d at least see the argument that there was some attempt to replace it.
Needing a local server and the lack of container format also makes preservation messier.
* sure, a subset of it was replaced for popular usage and even some of it is still technically possible, but good luck with that. I’m pretty sure communities around that are more dead than Flash was before the end, and maybe even still (for instance, NG with Flash Forward jams).