> I can easily imagine someone who is on their own for the first time suddenly realizing they don't really know how to make new friends or talk to people

I can't. If you have trouble making friends that's obvious long before college.

> But lots of people are not going to initiate an interaction, even if they are lonely. If someone else does, though, they will engage.

People shouting nice words at me gives me the same vibes as a stranger asking "how are you?" as a greeting, just more aggressive and annoying. I may engage in a conversation but not if it's generic smalltalk.