This, in part. The swift deprecation of XUL extensions felt like a kick in the gonads and made me switch to Pale Moon for a while, after which I landed on Firefox ESR to avoid the inmediate impact of bad decisions, and accumulated a veritable landslide of user.js and userchrome.css tweaks I keep having to maintain.

On the other hand, part of the struggle was my fight against the web as a """platform""", with its many privacy and security issues that accumulated as W3C APIs were added like hot cakes and websites exploded in complexity. Firefox provided the control necessary through addons, thanks to its vast community of likeminded people. Nowadays, a lot of the privacy controls have landed in firefox proper, in part thanks to the tor browser upstreaming, if you know where to look.