Nothing wrong with implying that people ought to behave according to mainstream social norms.

Isn’t that the same as saying that counterculture, fringe culture, and subcultures ought not exist?

I wouldn't take it that far, individual rights are important but so is functioning society. Counterculture is often a cyclic/youthful reaction to things that have been established as "better" or "proper" by older generations. Most rules for life such as the 10 Commandments have sort of a "deny youself some pleasure because it's better for the group" vibe that have been learned and re-learned over many centuries.

Interestingly, when most people simply choose to do what most people choose to do, you get an emergent 'herd mentality' which can lead to some very strange places. It is also sensitive to very small purturbations - which in real terms means, the one person who does manage to think for themselves may find they have an outsized effect on the direction of the crowd.

I think this mentality is also where the term 'sheeple' comes from.