The Register discusses how Intel's x86 everything strategy is to blame for this, you can read it over here.
In the middle of the last decade, Otellini knew that technology was going mobile and that ARM was then best suited, from a hardware perspective, to deliver greater mobility. He pledge to aggressively drive down Intel chips’ power consumption to a point where x86 processors could match the energy efficiency of ARM devices.
Eight years on from Otellini’s elevation to CEO, Intel can argue that it’s there. It has x86 in smartphones and, unlike previous attempts, they don’t deliver a much shorter battery life than ARM devices. The problem now, though, is that the rise of ARM in the interim has eroded the compatibility value of x86.