[dennis_jeeves]

>What core advantages would joining this group bring to its members that can't be acheived through careful social network screening and common sense?

The advantage here is more to do with the number of individuals. You are correct I do the exact same thing (through careful social network screening and common sense,) but that is limited to my known social circle. Here I'm doing it with total strangers. As to the specific advantage - well it's too generic and huge a topic. Essentially it's the 'advantage' of dealing with level headed people. ( to give a concrete example I have lend money to someone who could not have normally borrowed that amount from a bank).