Who's an end user.
Unless you own your hardware, you aren't the end user. When your phone, tv, camera, or even laptop on a non-free OS is on your network, you can get some semblance of control by controlling what network services it uses.
Things like DoH are part of the removal of my control as a home user and give it to Sony, or Apple, or TPLink
The most obvious thing is it becomes harder to block adverts.
Throw in internet-centralisation through HN darlings like cloudflare and you're screwed. You have no idea what anything is talking to, as it's the same destination IPs, so the choice is either block it completely, or allow it with no control.
> Who's an end user.
I think in this context it'd be any netizen who does not hold a significant amount of power to influence other [unrelated to them] netizens?
Every technology has both pros and cons. Those who develop standards must weigh both sides rather than considering only one of them.
In countries where the internet is subject to censorship, as well as in regions with underdeveloped infrastructure, DNS queries are highly likely to be deliberately tampered with, poisoned, or hijacked. DoH is a very practical way to mitigate this problem, and I do not believe that the ability to block advertisements is more important than that.
Moreover, advanced users can still run their own DNS services for ad blocking, and, at least for the foreseeable future, DoH will not prevent them from continuing to use traditional DNS. You cannot criticize an important improvement in security merely because it makes ad blocking less convenient. Other people may face threat models that are a hundred times more serious than yours.
I do share your actual concern, but I think the term 'end user' applies to any human sitting in front of a computer, trying to achieve something, independently of whether the effective sysadmin works against his interests or not.