> But there are other times for that, why in a meeting?

If you're in-person in an office, there are plenty of times for random social interaction. If you're full-remote, pre-meeting/post-meeting time is a low-friction source of social interaction.

I agree maybe ideally not in a meeting, but humans are imperfect and the larger the number of people invited, the greater the chance it’s going to take a few mins for everyone to arrive. So inevitably the folks who are prompt do some water cooler talk while waiting, and depending on the day/group/topic the water cooler talk might even extend a few mins after everyone has arrived, especially if people are enjoying the convo.