I think you're overestimating this one blogger's reach vs. 500/X's Facebook likes, checkins or comments (X being a vague social non-participation factor which is shrinking quickly). Consider the size of all those people's social graphs, how many impressions are made. The event would still have to be excellently run and inventive (like the Patron event in the article) to maximize impact, but I don't see a reason for such small groups like this unless money is literally no object.