A high-locality community might be one that serves a real town, perhaps even just a neighborhood. The referents and discussion are real to many, if not most, of the participants. You could get an answer to “What do you think of that new burger place on the corner?”
A low-locality community might be spread thinly across the globe. Members are necessarily a bit distant from one another and that burger place had better have a web site if there is to be any discussion about it! On the other hand, low-locality communities are more likely to have conversations on those many topics which, in a “physical community” cannot take place due to a very small number of interested people.