I joined when you used to have to belong to a university network and it tied into your university email account. It was a nice place for students so sure, and it was good to be exclusive. It kept things more intelligent at first and seemed more adult. This was the era of myspace and social networking really hadn't taken off yet. I guess the perception was that only 13 year old idiots and pervs join these contentless voids and that's really why I and my friends resisted at first. But then it started to become useful and we couldn't avoid it. Within 2 years or so, everyone was allowed on it and facebook changed it's layout and feature set about a dozen times to reflect this. It's less about professional now and more about social. Everyone is on it and the desire for exclusivity is long gone since we realize it's just better to have everyone on it. That's kind of the point of these things.