I've been using FF since forever (first Navigator, then a macos variant called Camino, and after it EOL'd, Firefox; tried quite a few others too, but always returned to FF). Never a problem, except of course with websites that don't test if it works on Firefox.

> shoot the messenger, it won't fix Firefox bugs or help their market share.

Your message doesn't really contribute to it either. If you hate Firefox with a passion and wish that Alphabet dominates the world and turns us all into clicking zombies, keep spreading it. Otherwise, better not.