I loved Flash, deeply, I learned to program in Flash. But I am slowly in the process of doing a 180 on this, where before I felt like we had lost something with Flash that nobody had ever replicated. People have different things they liked about Flash. I liked the animation-centered workflow (and I still think there's room for innovation in this space with modern tools). I miss the ability to export vector animations.
There's a technical hole that I still think could be filled by other programs today. But often, I hear people lamenting the loss of community and the loss of universal publishing.
And on that note, aside from the animation-centered workflow, I'm less certain that the rest of that stuff is actually gone. Unity publishes to websites just as well as Flash did, if not better. Unity even lets you publish to Linux, which Flash never really supported well.
And honestly, I'm not sure the community is dead either, it's just moved on to platforms like Scratch, Pico 8, Itch.io, and Roblox. I see very similar energies when I interact with people on those platforms. It's a different community, it's younger kids with different norms, the old generation isn't as welcome anymore. But I'm not sure the reason for that is because Flash died. Sometimes generations grow up and younger generations go act creative in different spaces.
So yes, there is a very specific workflow for a very specific type of game that no longer works on the web. I've used Unity, and I don't really like Unity, I hate it's resource management, I hate that we're still using proprietary software after so many years. But I think more people are making games with Unity today than were making them back then on Flash. It's more accessible.
I'm very, very slowly changing my opinion on this. Part of it is that Flash is still available today under Animate, and while it is still chained to Adobe I've still never heard a really good breakdown of how it's worse or what features it doesn't support anymore. As far as I can tell, you can still use Actionscript 3.0 with Animate. It is proprietary and expensive, but so was Flash -- so if it's purely a technical problem, then I'm not 100% sure that you couldn't still make a Flash website/game today.
I still think there's a hole here that could be better served by Open Source toolchains, but I'm becoming less convinced that it is as big of a deal as I previously thought. If you're trying to make games, now is a really good time to be alive. It could be better, but if you give me the option of making games in 1999 or making games today, I'm not going back to 1999.
And aside from that, even if Flash is a hole, it's still very specifically a hole for games. Even during its heyday, building static websites in Flash was a sin. Almost everything else you want to use to build a static website is still available. Just not that specific sinful part :)