I once went along to play at a jam night and found myself surrounded by people who wanted to tell me their stories of past glory and generally bounce their incomprehensible soundwaves off the side of my head. I quickly discovered that it is not for me. I have a friend who is a regular at one where I used to live and because he is the only bassist in the place who can play, he is a minor celebrity.
I appreciate they have their uses and, done right, can be a really good fun way to connect with musicians, but it just isn't for me. I'd much rather go and sit with my guitarist and bash out some tunes