I understand the appeal of that for developers but it comes at the cost of users agency and control of their own system, I've been very annoyed with even simple UI changes in firefox updates as I simply didn't ask or want any such change. Reading other comments here it's clear I'm a dying breed of old and stubborn users that prefers full control and agency over my own system. Making it easier for web developers to implement new features is absolutely not a tradeoff I'd make willingly at the cost of my systems consistency and reliability. Also the reason I use firefox is because of all the major browsers vendors they seem the most aligned with those values although this seems to be changing more and more every year.