Well, look at the way it works.

Let's say there's 100 miners mining HubskiCoin. There's a fight amongst the factions because some people think the color scheme should be "clean" while some think it should be "asphalt." So there's a fork - 35 of them go and mine "asphalt" while 65 of them mine "clean."

Everybody with holdings in HubskiCoin now has 35% of their holdings in HubskiDark. Even the guys mining HubskiDark still hold all their HubskiCoin. But now their mining efforts are being rewarded in HubskiDark, not HubskiCoin. Their pool is 35. HubskiCoin only has 65 miners but they represent the majority stake. If they can attract new miners, they have a bigger network. But look -

If HubskiDark attracts seven miners and HubskiCoin attracts seven miners, there's 114 miners. You don't get to double-mine. Every single miner could fork off the network and there'd still only be 100 miners. Mining capacity does not change. Total hash of all combined networks is the same as total hash of the pre-forked network. It's not like everyone gets to summon network availability out of thin air.

Forks are very different than ICOs - most every ICO out there is effectively a "subroutine" running on the Ethereum "program." Their hashes and shit are part of the payload of Ethereum mining.