You're so damned uptight. What's wrong with people meeting other people? What could possibly go wrong?
Well, some people just think differently than you, O Mighty Extrovert. But we're trying.
For me, it's all about maintaining a harmonious social tenor. Like many people, I do different things, and have different types of conversation, with different sets of friends. For example: Illuminati with Beth and Graham would not be fun, nor would I enjoy discussing politics with both of you together, or with you and noted paleoconservative Aaron Jubb for that matter, but those are key Graham-activities. Likewise, I have some friends who think sitting around and talking is great and some who might whine about how we should "do something." I'm generally good at predicting who would mesh with whom for me, but I'm not perfect at it so I get nervous when encountering new combinations.
This line of thinking also leads me to the conclusion (shocking, perhaps, for an extrovert) that having all my friends in the same room would not produce the maximum amount of fun.
Hey, you stole my link!
I knew it seemed familiar...