If they made it a DirectShow filter, then this would work for more than Edge, but that would go against their marketing desires of being able to say "only on Edge"...
Or perhaps that's already how it's implemented, but gated behind some checks that it's running inside Edge. I absolutely loathe this trend of taking a powerful and generally useful feature and severely crippling it for marketing reasons.
"eventual" in Microsoft terms is a very, very long time, and I can safely say that a lot of DirectShow-based stuff has specialised hardware behind it too. Of course the core of my argument doesn't change if I replace DirectShow filter with its Media Foundation equivalent --- generic video processing functionality available to all applications on the platform, vs. being bound to one and restricted to a narrow use-case.
I can kind of see why this might be Edge-specific than Windows-specific, since Edge is platform agnostic (it's just Microsoft Chrome, after all) and having the Windows implementation be DS/MF-based would be repeated, additional work from a broader, Windows agnostic perspective.
It would make sense from a "Windows first class citizen" perspective and I prefer Windows's "operating system is the central datastore" approach to media filters, of course. Linux's "BYOF" ("Bring Your Own Filters") approach sucks arse.
You could use Nvidia Image Scaling on mpv, which I mentioned in my other comment with more details: https://news.ycombinator.com/item?id=35051351. I find it better and sharper than Edge's currently.
Or perhaps that's already how it's implemented, but gated behind some checks that it's running inside Edge. I absolutely loathe this trend of taking a powerful and generally useful feature and severely crippling it for marketing reasons.