Actually Apple had to ask Intel to create a new SKU for the original MacBook Air.
Intel didn't have mobile CPUs able to fit in such a small/thin laptop as the one Apple wanted to design, so Apple asked Intel to create a new version of the Core Duo that was 60% smaller than what was available on the market (the CPU die itself is the same size, but the package that actually sockets into a motherboard is typically much larger and thicker than the die to allow wider pin spacing and reduced mechanical stress)
After Apple's initial success with the Air, Intel started selling that special SKU that was originally Apple-only to other OEMs, and later started pushing the whole Ultrabook thing. I'm not saying you should give Apple credit for "innovation" for making a thinner laptop, but they did innovate by figuring out what was stopping them from building something smaller and thinner than anyone had previously, and went to Intel (and other parts makers, I believe) and got what they wanted. If Apple hadn't gone to Intel asking for this, there might still be something like "ultrabooks", since sacrificing performance for portability has become practical for more and more people for whom CPUs are already way more than fast enough (i.e., this wouldn't have worked 10 years, a CPU that could fit into such a small package would provide performance far too pathetic to drive Windows) But they might not be quite as thin as it isn't clear that Intel would have offered these smaller models of their existing CPUs without Apple originally requesting it....or they would have come along much later.
Point is, Apple took the risk in creating something when no one was sure it would be a popular product. All of the effort in designing and marketing the Air would been for naught had it been as poorly received as, say, the Mac Cube a decade earlier. PC OEMs like Dell, HP, Lenovo, Acer, etc. operate on low margins and thus tend to play it very safe. New product ideas come from the risk takers, not just Apple but also the small botique PC makers. The big guys take ideas from them too, or in some cases just buy them out entirely (i.e. Dell buying Alienware)