You can't be a Bossy McBosserson and get big bossy promotions if you can't poke and prod your employees in person all day.

There are good reasons to go advocate for as few people in offices as possible though. Keeps people off roads, less traffic and pollution, those previous offices could be reused as homes that most cities desperately need.

I also don't see the point of an office when you only have a fraction of the people there.

I don't know any WFO advocate who thinks that everyone must work from an office. Managers saying their workers must work from an office doesn't do that from the perspective of an WFO advocate, but to make their workers more efficient as they think that office workers perform better. Similarly managers who forces all their workers to WFH (by not having an office) doesn't advocate for everyone to WFH, rather they think that it is more efficient to work from home so that is how they run their team, there is no grand social statement about this.