Completely changing the underlying architecture wasn't something that was known to always work back then, especially when it meant ditching your own PowerPC alliance. Despite the Jobs Reality Distortion Field on 11, those chips were not performant when compared to the competition. Much was promised, little was delivered.

Gather 'round and we'll talk about clones next!

Up to that point, their marketing had long been derisive of Intel parts and overstating the supremacy of PowerPC. (Supercomputers, anyone?)

It's marketing, that's what it does, but an about-face like that is eyebrow-raising.