https://twitter.com/BrendanEich/status/1217512049716035584/p...
https://twitter.com/BrendanEich/status/1217512049716035584/p...
For example just look at the alert popups[0], or the non native contextual menus, or the video pop icon. The UI is full of little quirks like that. The tab bar is by far the ugliest one of all current browsers, at least on macOS.
It also misses important features such as multilingual spell checking. For people writing in multiple languages it's a real PITA. I know this functionality can be added with an extension but it slows down FF too much IMO.
The polish of developer tools has exactly zero to do with a browser's popular marketshare.
All the people I know, who left FF, myself partly included, did so for this reason. Quite some sites did not work anymore on firefox. And the normal user does not care that this is because of vendorprefixes which are not standard. They care about that their website does not work anymore.
Keep the webdevs ... keep your users.