They just want people to come back to justify their corporate lease / rent on whatever offices they have. That's really what it's all about. All their productivity claims are bullshit.
I don't suspect any grand conspiracy, but I do think a lot of asset managers have had chats with high net worth individuals and gone over just what the collapse of the commercial real estate market would look like for them personally, especially with the stock market being so shaky as of recent.
I suspect these causal conversations are behind a large number CEOs return to office strategies (in addition to justifying their office investment as you mention) as well as Malcolm Gladwell's sudden revelation that working in an office is super important for everyone who is not him.
That’s still not a good reason, since you are essentially trying to guilt people into staying or making their life more busy so interviewing is harder.
I will say I've been work from home for years now and I still do all of those things ;). Just not with my coworkers. And not always in the heart of downtown, but more local to where I am.
The money is still spent, just not in the same places.