Why would investors want that? The building's already paid for. It doesn't seem like putting people into it or not would matter at that point, assuming RTO is employee performance neutral. And unlike executives, investors have no need to fool people into thinking they're making sensible decisions.
Those buildings will be worth much less if the culture of working from home becomes ingrained since the demand for this type of office space will permanently decline. Those who invested in office real estate may stand or fall with people returning to their offices.
Maybe they feel hurt every time they are reminded of the empty buildings because it's a waste of money and to get everyone back wouldn't hurt anybody in their assessment, it's actually how it was done before and it worked well, yadda yadda, so why not.
I do think the reasoning applies much better to executives, though.