This is an old tradition.
Cafes, bars, tea houses, etc have served as social hubs and placed to read or work on documents (now computers) for literally thousands of years, everywhere on the planet. There's simply a social need for a space like that, because it's a more efficient usage of space to have people work on a revolving basis in a shared space than everyone have a private space of their own or not be able to work.
It's only with the modern invention of corporate coffee shops that misvalue social fabric that we see the churn happening. (PS -- those corporate stores are wrong about the short term boost from churn improving their long term fortunes, at least from what I've heard from the big ones.)
I also find it interesting you approve of one "office-like" usage -- having a chat or meeting -- but disapprove of another -- working on documents.