I'll write an unpopular opinion:<p>1. Developer's time is not a commodity. The time you spend testing in alternative browsers is time you can spend in tasks that will make life less painful to the people who work with you such as writing tests, documentation, or new code.<p>2. A website that only works in Chrome is preferable to a website that does not exist. The business should be the one who dictates which browsers should be supported, and it should be a rational decision based on data such as reviewing your own analytics. Nobody has infinite resources.<p>3. Using a website is a privilege, not a right. The same way you are free to choose your favorite browser, a website owner is free to choose which users to serve, the same way we can say "Are you still using IE8 in 2019? tough luck buddy, the site is broken", we can also say "Sorry dude, I didn't care enough to support Firefox because X feature was broken".<p>4. When you as a user decide to choose Firefox because "my ideological reasons", you are also choosing to deal with the negative aspects such as broken websites, broken extensions, lack of features, loss of mindshare, etc., etc., if you don't like dealing with them the alternative is pretty simple: Use Chrome, that's what the end users do anyway.<p>The reason Chrome has gained lots of mindshare is because we all love convenience, and there are less-painful alternatives to push the "we don't like Google" agenda such as forking Chromium. The "we don't track you" is a huge competitive advantage against Google, why should you give up everything that Chromium does right? The resources that Mozilla spends maintaining Gecko could be used more intelligently to build for example a security team to alleviate the concern of having a huge common attack area.<p>Wasn't "test once, run everywhere" the holy grail? Or now we like O(N) instead of O(1)?