I agree, but one thing is to demand all your users to be on the latest Chrome, and another one is to support browsers that are no longer maintained and contain security issues (IE). If we discourage people from driving old insecure cars, we can also discourage people from using old insecure browsers.

Ideally we could section off some minimal baseline functionality that could be implemented more securely than the whole modern stack. Just HTML and a little CSS or something. Then mandate that, at least, services provided by the state should be accessible in this baseline functionality mode.