Not to mention ARM chips which by and large were/are more efficient on the same node than x86 because of their design: ARM chip designers have been doing that efficiency thing since forever, owing to the mobile platform, while desktop designers only got into the game quite late. There's also some wibbles like ARM insn decoding being inherently simpler but big picture that's negligible.

Intel just really, really has a talent for not seeing the writing on the wall while AMD made a habit out of it out of sheer necessity to even survive. Bulldozer nearly killed them (and the idea itself wasn't even bad, it just didn't work out) while Intel is tanking hit after hit after hit.