Everyone has their own approach to social networks. Some folks won't make introductions, preferring to keep themselves at the center of the exchange. Others are happy to connect two people who can help each other. Likewise, on the professional online social nets, some equate connecting with the informal action of exchanging business cards while others feel such an act is more intimate, available only to close colleagues and partners.
My social net of choice is LinkedIn primarily because i use it as an evergreen address book to get updates from my connections rather than to really seek out those I don't know. Accordingly, and because a contact can't really do anything to your network without my explicit approval, I tend to approve most of the connection requests I receive. (With two exceptions - those who seem to be nothing more than LinkedIn Whores - "5000+ CONNECTIONS - MEET ME" - and those who spoof employment at Google in order to invite their "colleagues" to connect).
Since we all know about the "strength of weak ties" this strategy seems pragmatic. So this past Memorial Day weekend I took a step deeper into the LinkedIn World by uploading my address book and sending connection requests to about ~400 people whom i've met over the last seven years. These were folks already part of LinkedIn and represented about a third of the people from my address book that were already in the service and not connected to me.
Imagine my surprise when this action caused my account to be temporarily suspended. What did i do? How do i get out of jail? Was it some velocity tripwire? Did i need to upgrade to a premium account?
A little digging into their customer service department (via the help of a LinkedIn co-founder who has since left the company for his own start-up) got my account unbanned, but only after i acknowledged my misdeed via email - the equivalent of writing it on the blackboard 500 times after school.
What was my offense? Turns out if more than five people say they "don't know you" in response to an invite, you're blocked as a spammer. They wouldn't tell me if those strikes expire over time or not but they were clear that it wasn't a percentage of invites, but a fixed number. So although several hundred of the invitees accepted my solicitation, the few who didn't remember me got me banished to Reid Hoffman's purgatory.
Net effect - a tiny loss of goodwill and a more conservative approach in sending out invites - which i guess possibly slows their network effects, but they'd argue that LinkedIn is a Strong Tie service. Or at least the Weak Tie service is their Premium Version which charges to you connect with those who "don't know you" :)