> Many banks and government websites don’t even support it

Because their web developers are too lazy to write anything to proper standards. They're doing some kind of lazy "Check for Chrome, because everyone must be running that, if not, redirect to an Unsupported page".

I've yet to find a website that "refuses" to work in Firefox which doesn't work just fine when I use a user agent switching extension to present a standard Chrome on MacOS or Chrome on Windows useragent.