Something that I think needs to be remembered is that socks provide a service beyond getting that person another gift. There are many instances in small fandom exchanges I've run and socked up where my sock ended up being the only recipient for a participant. That person would have had to drop out if my sock hadn't been there, and who knows what that would do for their assigned writer if they were also in the near-unmatchable boat.

If socks are asking for the same 3 fandoms across 9 accounts that's something different but IME most socks are the Pear Tree challenge asking for different fandoms each time. Others want and are able to sign up because they see somebody is requesting their fandom that nobody else requested.