As a Firefox user, I still run into sites today that are broken unless I switch to Chrome. Less so for Edge, but double for Safari.
Since its inception the web has always been a hodge-podge of half-implemented standards and deliberate violations of same in an attempt to capture marketshare.
That said, it is the easiest/laziest way to get something ***cross-platform.
*** Really you’re just writing for the web platform that sits on top of other platforms. Browsers really are as complicated as entire operating systems today, with all the accompanying bugs, security problems, deliberate privacy invasion by design, etc. Meh.