system
A chat on subreddit /r/pcmasterrace
human
I ditched it for chrome because chrome was faster and it tied the Google services I used nicely together. I might go back now.
gpt
For a while it was worse then chrome. Memory leaks, bugs, playback in non active tabs not starting/continuing and more. The quantum redesign addressed a lot of the underlying issues, but left it striped of features. It removed a lot of compatibly, add-ons and features needed to be rebuilt. The mobile version got hit in the same way.

I can absolutely understand anyone who felt firefox sucked then as if you didn't follow the development this just dropped on you one day. Features you where used to gone, add ons and themes you where using not working and all while having less compatibility. Anyone that understands development understands that's a steeping stone needed, but many people didn't and switched. And once you have a new browser that does it's job well enough most people don't look for an alternatives or which one is the current best. Why would they if there is no problem.