I agree that once someone has been flagged a couple of times that their items are fake they should be banned.
But seeing as ebay do nothing to veto their members, there's nothing stopping that guy just opening a new account with a new email (other than the obvious loss of feedback that can be artificially generated)
It would make the honest people more likely to sell something.
I sell my items cheap, because I buy them cheap, I'm happy if I make about a 75% profit. But I personally check my items before I post them with any guides I can find on the internet that say how to spot a fake.
My items are bought from bankrupt/liquidated businesses and surplus stock, one mans loss is another mans gain as they say.