You're still right that plenty of people make irrational decisions under whatever incentive structure they're in, but I think that the steelman version of GP's argument would probably go something like:
If we see a large % of companies going full-RTO, then maybe there's something to be said for the bet that RTO is a long-term competitive advantage.
If there is a very strong impact on competitiveness, maybe we will notice in about a decade, if companies don't collude in stopping it.
Person flatly said no one works in WFH. I am also a manager and responded my team busted their balls the whole time, and delivered results. My personal opinion is my team did 120% of their productivity. I also acknowledge that some people are not built for it and their productivity may fall. I believe a manager can deal with this (either creating the right task-incentive structure, or getting the person off the bus). After my impassioned argument, the person said ..nope .. people just don't work during WFH. This was a social event, just the two of us talking, so I am quite sure this guy was being honest.
I also ran into a different person in a leadership position (just not very high; more like technical leadership; ex-professor; stints at Google). He was convinced the real reason FAANG hired so crazily was because productivity per employee had dropped dramatically. His belief was no one worked during WFH. Again, my impassioned arguments and personal anecdotes did not really move this person.
TL;DR: if there is no data, decision makers are going to stick to what they know best. And what current execs / c-suite knows best is in-office. They haven't learned management techniques for fully-remote yet.
I also started compiling research showing the value of in-person interaction: https://news.ycombinator.com/item?id=34673235