Yes, I have seen your frothing Reddit posts, you don't have to repeat them here. "Leftist fascist"--can I give you a bit of free advice? If you have to modify "fascist", everyone and their dog knows it's because you have to modify your slur to make the mirror a little more palatable. Maybe find some new ones.
But I reject the square-peg premise you're trying to jam into that round hole anyway, as it's not a democracy, either. Your choices impact your neighbors without their consent. It's not about fucking over power users or whatever the weird little epistemic enclosure you come from wants to insist it is, it's about addressing technical debt both in terms of performance and security--and the latter matters quite a lot in terms of not enabling people who think they're power users to 1) blow their own leg off, and 2) blow the legs off the people next to them. That's why those "leftist fascist" evil scary Firefox people decided "hey, let's patch some of these up."
Customization, in and of itself, is fine (modulo the combinatoric explosion that leads to security holes). Few enough people would disagree with that, though I understand that the aforementioned epistemic closure holds as axiomatic that everybody just hates the tweaker types. On the other hand, customization at the expense of competent security development, which is what you get with Pale Moon, is not. And seeing as how there certainly doesn't seem to be much in the way of developer competence, to the point where "don't use the stuff that upstream has working just fine because we can't figure it out" is a legitimate attempt at "discussion", it ought to be dumpstered.
Somehow, this "power user" (god, I hate that term) gets by just fine with poor, benighted Firefox--having switched to it from Chrome/Safari after Quantum because it finally felt as pleasant to use as back in The Day. Clearly, though, that just makes me a radical-left SJW hater or something. But that's fine. Modern Firefox is heckin' great.