You're thinking on a very narrow definition of a contract, here's a simple contract example that's currently being censored and wouldn't be censorable on Blockchain: Buy NSFW games.
A simple contract could sell you NFTs for game keys that could be redeemed on Steam/Itch/GoG or even the own dev site. So there's no middleman who could oppose this transaction and say which sort of games can or can't be sold. This whole thing would be completely automated, secure for every part and non-censorable.
You're hearing contracts and thinking on paper legal documents, whereas smart contracts usually refer to programs acting on tokens, the code that acts on those tokens is the contract, in the example above the generation and transfer of the tokens would be the contract.
So? Just use another exchange, that's the same as saying paper money is bad because pawn shops might ban specific users.