You don't own the roads in Detroit; the government owns most of them.
Gmail is not a government service. Google is free to make that work with only one browser, if they want.
You can't assert that Google must make Gmail work with any browser whatsoever, because that means supporting someone using Windows 95 with Internet Explorer 5.5.
I'm not going to waste my time explaining to you what a metaphor is, but I will say this Firefox was the dominant player in the 00's 2010's when they did this, not the 2% market share it is now.
Gmail is not a government service. Google is free to make that work with only one browser, if they want.
You can't assert that Google must make Gmail work with any browser whatsoever, because that means supporting someone using Windows 95 with Internet Explorer 5.5.