Many processing units can offset this via superscaler methods, that is tricks to have more than one instruction processing at the same time. pipelining, speculative execution, smt, etc.

The article does not go into great depth about it, but does say that the 1 ipc ratio number is based off more gut feel than anything else. I assume the idea is that the superscaler bits(greater than 1 ipc ratio) help compensate for the slow bits(less than 1 ipc ratio) normalizing out at around a 1 ipc ratio when your code is good.