Back before I entered geezerhood, I used to find festivals great places for one-night stands and weekend romances -- of course, that WAS back in the '70s and '80s mostly -- but, as with pubs, I haven't personally found party atmospheres and booze to be great tools for initiating real relationships.

Mostly, I find festivals good places for singing and dancing with other people "in the moment" and enjoying the company, often without even exchanging names.   I think a lot of people experience them that way. But I guess if your intent is to connect with people you'll continue seeing after the festival, they can be good places for that. The smaller regional music camps, such as Singtime Frolics (Oregon), RainyCamp (Washington), etc., do seem to be prime soil for budding romances.