> DNS over HTTPS is a trojan horse to allow application developers to subvert the system administrator's DNS policy.
No, it's a very important tool to help users bypass censorship and surveillance performed by hostile network operators.
> Specifically, so that companies like Google, Microsoft, Amazon can ensure that you cannot prevent ads being displayed in their little black boxes (hardware or software).
They don't need DoH to do this. They can do this by either hardcoding the IPs of their ad servers, or by serving their ads from the same hosts as the content you want.
> This is dangerous, anti-user, and should be avoided at all costs.
No, it's very pro-user and should be used at all costs.
> DNS over TLS is the correct and appropriate solution here.
No, because that's too easy for the aforementioned hostile network operators to block.
> You can ensure your (Firefox) browser does not use DNS over HTTPS by configuring a canary domain: https://support.mozilla.org/en-US/kb/canary-domain-use-appli...
This is a misfeature that needs to go away. Thankfully, Firefox has an override that lets you manually enable DoH even if a hostile network operator configures that.
> but let's be clear here, nobody besides Firefox is going to respect user choice about using DoH.
Correct, but not in the way you meant. Most operating systems and programs will never use DoH even if the user does want it.