Is that an intentional paradox?
The fox will eat the sheep if unattended by the farmer but the farmer must leave for 20 minutes each day and must keep the sheep safe. He can't take either with him and no one else is allowed to watch. Solve the problem (without digging holes or building fires).
All the farmer has to do is shot one fox and then hang it outside the farm and the rest of the foxes will get the message.
And we even have the equivalent in the real world, the justice system and the prison, all we have to do is raise the punishments to a ridiculous level so that nobody will even think about it, especially since this is nothing like a car accident, a brawl in a bar that might get horribly wrong or anything like it, those guys plan the attack for days, it's nothing built on an impulse.
Back to the main question, no we won't have a perfect exchange, we won't have one without blocked accounts, poor customers service, unhackable and with low fees.
And DEX are a joke, I feel safer with bitstamp or bitfinex than with some so-called decentralized stuff which is actually run by somebody and dealing with a total stranger via some 3 party payments. I would rather go to localbitcoins and exchange there.
Oh, and I don't care at all for shitcoins so in my humble opinion btc<>shitcoinsexchnge have no purpose in this world.
LE:
Wait till binance shart dealing with $, then we're going to have a real shitstorm of complaints.