So now you have to coordinate on Slack to go to one of the shared team meeting rooms instead. At that point you might as well have your conversation in Slack, even if the person is sitting right next to you. And that's the state of open offices today, co-located but void of any actual collaboration.
I've worked in single person offices, 2-3 person offices and open offices. 2-3 person offices where everyone works on the same thing is the best, by far. Remote work is the new private office, not quite as good as a 2-3 person office, but infinitely better than an open office.