Yeah, I don't see how the maintainers can patch security vulns or add support for newer web features (e.g. CSS variables) when the upstream fork is no longer maintained. They would have to write the fixes themselves, which just does not scale for a project that has 1 or 2 developers working on it part-time.
I think we're at a point where there are enough sites out there that we can avoid a good portion of them (i.e. ones written without progressive enhancement in mind) and still be happy.
For example, I am quite happy with visiting only sites which do not require JavaScript, do not use cookie banners, paywalls, and registration prompts.
For my purposes of browsing Teddit, HN, and my own websites, there are more than 20 beautiful, usable, friendly browsers I can think of just off the top of my head.
For everything else, I just close the tab and move on. Past experience leads me to believe I'm not missing much, because sites which break these requirements usually have crap content too.
If I really need something, I can open Chromium (with UO and Vimium) for that particular site and then close it afterwards.
It feels to me like "my" Web has already passed the bottom of the valley, and is only improving with time.
Only a couple years ago there was no Teddit or Nitter, and now they are here.
I'm finding more and more usable sites almost every day, and I'm missing anything less and less frequently.
A couple years ago, I was mostly down-voted for pleading for noJS support here on HN, and now it's the opposite.
I'm feeling optimistic. The biggest thorn in my side right now is SSL/HSTS, which is a very fast treadmill. I'm praying for an easy-to-use and transparent SSL-stripping proxy I can use in the near future, which will make things even better on machines I control.