That's a very legit point. The various features of FB events make them "stickier" (or whatever the buzzword is) than regular advertising...the feedback options, with prospective attendees asking questions and seeing how you respond to them, is also likely to boost interest. It's not quite fair to say "Oh, this is the same as Craigslist ad postings, except you paid" just as it would be silly to ignore Airbnb because it seems just like paid Craigslist ad postings.
That said, given the nature of the niche market here (though you probably know better than anyone), it's not clear that the success would easily apply to other kinds of businesses...or phases (i.e. a startup trying to get attention vs. a business having a out-of-business clearance sale).