For years Facebook has been trying to solve a problem with people who spam lots of unknown people with friend requests.
Previously, Facebook kept track of users whose Friend requests were often declined--but that didn't detect the spammers because a lot of spammers look like someone you "might" know, so users would tentatively accept the friend requests just to see who it was, then block them later. It also generated a lot of false-positives. And it didn't help with the spam.
Now whenever someone responds to a friend request (both for accepting and declining) Facebook blandly asks "Do You Know This Person Outside Facebook? Yes/No". If too many users answer "No" to this question Facebook will start restricting whom you can send friend requests to, even if all those users accepted your friend requests. Unfortunately lots of people are misunderstanding the purpose of this question, and clicking "No" for anyone they don't know in person
, even though the person might be known to them
. This is probably what happened to you because you have so many "internet friends" whom you haven't met personally; your friends didn't mean to punish you, but some critical number of them probably misunderstood that question and hoodwinked Facebook into restricting you.
The question is badly phrased, and users are misunderstanding its purpose. It ought to say something like "Do you know who this person is?" or "Have you heard of this person?" to discourage people from choosing "No" for friends they actually do know.
AFAIK Facebook hasn't commented publicly, but they can't be unaware of the problem. Lots of users are discussing it, like here
and elsewhere. Facebook will probably take another stab at it eventually, and it'll probably cause new problems.
Offhand I don't know how to get yourself un-restricted, but I'd be happy to try the "Friend suggest" feature if there's someone on my list that you want to add. That might be a workaround.