[zzzcpan]

Another reason why this is not a fundamental problem is that a user agent made for the user would have to violate and ignore most of the standards anyway in order to honor user's interests. Reimplementing all those corporate and ad tech driven standards is simply a waste of engineering, if anything it will only hold back anyone attempting to do it and won't let them compete.

[AgentME]

What specific standards would a user-respecting browser not implement? I can't really think of anything besides maybe EME and third-party cookies, though it's not like those are really core features.