I get that breaking split horizon is a real concern, but also I would expect any enterprise deployment using internal DNS resolvers should be able to set up its

I get that breaking split horizon is a real concern, but also I would expect any enterprise deployment using internal DNS resolvers should be able to set up its users' Firefox config to either a) point at an internal DoH server, or b) turn it off? On one hand, I see the arguments against DoH-by-default -- loss of control, potential for unfixable poor / buggy implementations, requiring trust of third parties... (The trust problem isn't going to be solved any time soon, though.) It would be nice if implementations just used the discovered DNS server across the board, but DNS servers don't support DoH across the board yet. On the flip side, I don't see any widespread shifts in this space until a large enough player (in this case, Mozilla) decides to put its thumb on the scale to "encourage" wider adoption. While centralized DoH may be the only game in town today, I would argue that's due to lack of adoption, and I would hope that's not the desired end state.