While all of that is true, I wonder how much of it is re-affirmation of a social hierarchy.

From the bosses point of view RTO is a costly signal that demonstrates how much people want to work for them - signals must be costly in order to be effective. Promoting WFO as more productive and less costly destroys the signaling aspect. Perhaps workers could offer other costly signals - maybe regular arduous in person team building exercises that management can show their friends photos. I really can't think of many alternative socially acceptable costly signals that can be required from employees which is probably why RTO continues to remain so popular.