I have trouble believing it's to do with commercial real estate because these $1T companies are holding, what, ~$20B worth of real estate? Why would 2% of their value ever be worth changing the way their entire workforce works unless they've estimated that the productivity impact of RTO could be at worse -2%?
Personally, I look at the incentives. Companies are incentivized to maximize their value and they have the most internal metrics on productivity compared to HN commenters and IC WFH advocates. So if they see productivity slump while WFH, they'll advocate RTO. Meanwhile, IC's care more about their personal situation than the company's value. If they like WFH, they will advocate for it, even when overall it negatively affects the company.
I think some companies that are high-achieving and very intentional are able to full-remote and get an edge by recruiting high achievers that will only remote-work (open-source leaning like Vercel, Gitlab).
But I think for the majority, the negative value effects outweigh the positive, and there's a reason Sam Altman and OpenAI are in-office only.