What it is about is that the defaults for pretty much all OSes are bad. Maybe if we lived in a world where DoH was shipping by default enabled in Linux/Mac/Windows and set to something private like Cloudflare, it would make sense not to even provide browser options at all.

But as it stands, the current solution (while a little unintuitive and hacky) give you the best of both worlds. If you're a normal user, you get secure defaults. If you're a power user, you can go into Firefox and point at your own DoH provider, or turn off DoH entirely if that's what you want. And if you're an admin deploying Firefox on a network, you can deploy it with a custom profile that sets its internal DoH/DNS settings to whatever you want.

Do you know of any references that describe how it determines if the DNS service offers a DoH option or not? I can't find anything more than vague descriptions.