These days "play online" so often means "play with complete strangers you've never talked to before and most likely never will again".
Even for large popular games like Unreal Tournament you typically joined a set of favourite servers, and had the same set of "regulars" hanging around.
It's like old-school relatively small-scale forums vs. reddit or Twitter.
You can still kind-of get this experience if you try hard enough, but it's not really the default and typically nothing is geared towards it.