The problem is that that doesn't really work. The people working in the office don't get the benefit of in person social connection if others aren't coming in, too. Either you have people coming (win for the office people, loss for the remote) or you have people working from home (the reverse). Leaving it up to everyone to work it out on their own doesn't really solve the problem.
That being said, working it out "per team" is generally reasonable. I've had hybrid stints, and I always coordinated with my team so that we all came in on the same day. Then we could do the social thing together at the office.
There is always a fraction of people who will chose to go to the office. That's enough to have social connection. These persons do not have to be on your own team.
The last 10 years or so I have been working on teams splitted in 3 to 5 different countries, and now in 3 different continents. In that case you are effectively working remotely even when your are working in a company's office.
Can't say I agree with that. Seeing "anyone" is not the same as seeing the people you're close to (work closely with, know well). It certainly doesn't bring me the same mental benefit.
It is not the same but having teams split in different timezones has other benefits and it is often desirable to work that way. One example: on teams handling operationnal roles having teammates in different timezones being primary responders avoid being on call outside of your office hours.
That being said, working it out "per team" is generally reasonable. I've had hybrid stints, and I always coordinated with my team so that we all came in on the same day. Then we could do the social thing together at the office.