Multipools aren't killing coins (directly).  They're killing the profitability of all the shitcoins that exist.  Nobody is bothering to pump & dump most coins anymore because any attempt to do so is met by a massive amount of mining power shifting to that coin and immediately dumping 100% of the newly mined coins.  Pump & Dumps are only profitable if you can fool enough idiots to bring the average bid price higher than your average price per coin bought during the pump up period.  With multipools, that just doesn't happen because they will dump coins to the highest bidder within an hour of the pump.

As a result, multipools are going to be fading away pretty fast.  The profitability is shrinking rapidly in comparison to straight DOGE mining (and if that fails, straight LTC mining).  They are a dying breed because pretty soon there won't be enough coins left for multipools to bother with.

KGW/DigiShield/whatever does nothing to prevent multipools.  It actually *helps* multipools because it means those coins will drop in difficulty quickly, returning them back into their coin rotation.  They prevent the coins from literally *dying* due to multipools, but their profitability is gone regardless.