Most had probably been warned before or were found to have been previously banned. (I assume that if you're banned once and come back without permission you will be banned again as soon as you're discovered.)
You would hope so and think so, but in this case you would be wrong.
If you ask me these people weren't "ZOTted", they were LOTTed. As in, they were banned for the same kind of reasons that Lott got in trouble for wishing Strom Thurmond a Happy Birthday. Some people are soooo afraid with being associated with some sort of perceived racism or racist slight or whatever that they'll throw good people to the wolves. In my opinion, most of those purged are victims of political correctness. It is shameful that Free Republic is starting to go PC after all of these years. But, hey, it's Jim's sandbox. He can do what he wants...