I disagree, browser based games took a very hard hit after Flash was killed and the infrastructure that was built around these games died. Newgrounds might be still limping around, but pretty much everything else, like Kongregate now, has died and nothing replaced it (most of the sponsors that funded these games moved to mobile, but very few of the actual developers did and mobile games are very different than the more raw/brutal flash games you'd find on pretty much every flash gaming site out there).
The tech, from a purely technical and capabilities perspective, is better sure. But the ecosystem and tools are much worse.
This is a larger problem with software archival. I suspect a lot of the media created during the fledgeling decades of the "digital" era will simply vanish.
Capabilities are better, thanks to WebGL and modern JavaScript - and no proprietary tooling is needed, but the overall barrier for entry now is much higher: during the heyday of Flash any teenager could put together something silly, adapt, learn, improve, and beyond. You can’t do that anymore because there is no good, well-supported, code-free way of making art and animations without writing any code for HTML5+Canvas.
None of the kids that got started by making silly animations in Flash back in 1999-2007 could do that today: there is no paintbrush tool for the web.
I understand that Flash's HTML5 support requires a Flash document to created from scratch to support HTML5 and it doesn't support the same features as SWF - but I might be wrong.
My favorite, which was acquired by Kongregate in Dec 2019:
https://surviv.io
2D Last Man Standing. Great fun.