Earlier quoted context omitted.
> I wouldn't seriously consider using a non-free application for something as essential as everyday web browsing. Why? Are you considering forking Firefox?
For clarification - if you either contribute code or money to Firefox, you are clearly supporting the existence of a free browser. I don’t see how just using it does. So if you aren’t contributing to it you may as well use the browser with the best feature set for your use case.
lower market share =>
nobody testing against the free browser or fixing site breakage =>
quirks (bugs, underdefined specifications, nonstandard features) of other browsers becoming required for a functional Web =>
free browser is no longer a browser of the actual Web.