I know this has been discussed previously, but one problem is how do you know who is part of a pool? I could set up 10 pools (10 servers) with 6% each and then they'd be under the threshold individually, but I'd control them all.
The idea would be to make a Prisoner's Dilemma that would encourage defection. This would not work if you were one person who owned all 10 pools; but if the 10 pools were a loosely-maintained conglomerate, then the conglomerate would fall apart because the first group to defect from the conglomerate would get some sort of reward at the expense of the rest of the conglomerate.
As a miner, one could easily send 10% of your hash power to each of the sub-pools, with a switchover at say at midnight UTC on one day to avoid the penalty. Or, even easier, the pool operator could divide the hashes coming in 10% to each sub-pool and switch over all at once so. The miners would get the same reward. ;-) (It is a tough problem!)
The key is that without some type of central authority there is virtually no way to know who is part of what pool IF the pool/pool operator were attempting to hide it.
Some useful links if you haven't seen them:
https://en.bitcoin.it/wiki/Pooled_mininghttps://en.bitcoin.it/wiki/Mining_pool_reward_FAQhttps://bitcointalk.org/index.php?topic=18313.0https://en.bitcoin.it/wiki/P2Pool