There have been many hypotheses about why the push for employees to return to the office has been so strong, and I'm not arguing against them as they're probably all true to one extent or another. But for the majority of companies I believe the reason is quite simple:
Most executives and upper management folks hate their families and hate being at home with them.
Think about it. How many of the higher ups at your company are having affairs, or go out drinking every single night, or are always going on “business trips” to “conferences”, or finding any other excuse not to be around their families? I know from my personal experience it's almost all of them. In the office these are the same people that are flirting with (*cough* harassing *cough*) coworkers and making inappropriate jokes too. Basically, these people have no life, no real friends, and a shitty home life because they're generally unpleasant people to be around, so the office is their only escape and their only venue for forcing people to interact with them.