Pipeline myth

In the past few days I gave some Mac users the chance to convince me to buy a Mac instead of buying another PC and putting Windows or Linux on it. Since I argued that Apple processors are generally slower (oh no, I mean, run at less megahertz), somebody pointed me to http://www.apple.com/g4/myth/, a talk from Jon Runistein (Apple Senior VP of Hardware). He argues that the speed doesn not only depend on the the amount of megahertz as Intel pushes forward, but also on other factors. Jon calls this the "Megahertz myth". Sounded applausible to me so far. But what happens? The rest of the presentation is all about the fact that's the G4's pipeline is so much shorter (G4 is the processor Apple uses for their Macs).Apart from the fact that this presentation doesn't show a refreshing full picture that's kind of promised, it's all about showing that that the processors developed by Intel (both Pentium and Itanium) and Sun have so much longer pipelines, which make them very inefficient with a lot of branches. First thing I'm thinking is, why do others have such a long pipeline? I can't possibly imagine they just didn't realise it would slow the processor down that much... But even assuming they are that stupid, the pipelines are twice as long at max, but as those processors run at up to 3 times the speed of the G4, wouldn't that make it faster even if a longer pipeline is bad?