I have a weird idea, and no idea if it's possible:
What if the wallet used to mine (there is always a wallet, no?) checked to see if the hash on it was below 50% (or 40, whatever) of total hashrate. And if it isn't, it would be blocked from competing for a block? If pools ended up with wasted hash due to not watching their hash rate %, I think they'd invent a way to keep their hashrate down fast. But as for Dash, we just have to block >50% hashrate wallets from winning blocks.
make any sense?
Nice idea. But it probably breaks every principle of decentralization.
Keep scratching that head though, you're probably on to something.