> I still find some pages don't work 100% correctly in Firefox.
find that hard to believe. but even if you find something using an api not implement by firefox, chances are you definitely do not want that feature anyway, the firefox gave in to really awful stuff and only drew the line on obviously egregious privacy violation ones.
Sometimes devs rely on Chrome specific quirks, or are shipping broken apps that Chrome manages to make the correct guesses for it to be functional.
Many see 'it works on Chrome and mobile Safari' as 'it works' and they can get project signoff / ship / get paid / whatever and don't care about other users
The company that has the application may not know until a few users complain (if they complain) and by that point it could be too late due to the contract, or they may not understand what a different browser is or care either.
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...
I definitely run into pages broken in firefox desktop or especially firefox mobile. Extra especially on proofs of concept advertised here on HN.