Some ASIC chips don't attempt every value in nonce range. If the winning solution uses a nonce of 0x18392740 and a particular ASIC is not checking that value the miner isn't going to return a solution. You could send him the same work 1,000 times and he will NEVER return a solution.
so if miners are not equal, perhaps pools should be segregated? detection and enforcement would need to be worked out, but much more complex systems exist in this world