Relax, everybody. Fenix is a major rewrite. It takes time to reimplement all the WebExtension APIs. Nevertheless, the intent is to eventually add support for all the APIs that make sense on mobile. (See here, for example: https://bugzilla.mozilla.org/show_bug.cgi?id=1632626#c1, or just scroll through the list of bugs here: https://bugzilla.mozilla.org/buglist.cgi?product=GeckoView&c...)
If you go back and read old HN threads from the first public release of Fenix, people were afraid that the lack of extension support was a sign that Mozilla had given up on adblockers. I hope it's clear by now that's not true. (From what I recall of lunchtime conversations, back when those were a thing, the plan for extensions was "well, we're definitely not shipping without uBlock Origin, and we'll see what else we can get working from there".) Similarly, the fact that parts of the WebExtension API are not currently available doesn't mean Mozilla has given up on it. It just means that things take time. (If it were easy, other mobile browsers might support add-ons!)
It takes a lot of resources to support two parallel codebases. At some point you have to rip off the band-aid. The sooner Fennec is cut loose, the more effort we can dedicate to Fenix improvements (like improving WebExtension support). The transition was always going to be a bit bumpy, but things should hopefully get better from here.