And for regular DNS, their ISP/employer/school will be the service provider for 99.9999% of users. Regular DNS is not exactly easy to find (on Windows, it's under Settings -> Network -> Change Adapter Options -> Adapter Name -> IPv4 -> Properties), which is arguably as hard as going to about:config. And there is no menu of providers listed--nor does it explain who would choose the "automatic" DNS server options (the one that uses DHCP).

So the status quo is no better than this, and at least this is encrypted and protected by a privacy guarantee.

Now I agree that ideally a user-visible preference should be created for the DoH resolver, but I don't think that's a blocking issue. Just like the accounts features uses a mozilla server, and chrome uses google accounts, and both use google safe browsing lists, browsers have always made the decision to hardcode various external service providers.