Back around 2009 I had a little visibility into Intel's mobile efforts. My information is way out of date, but unless Intel management changed drastically, my hunch is that this explanation is still valid.
At the time Intel had already introduced some mobile silicon, but there was little uptake. So they were iterating; they wanted to improve for each succeeding generation. But they had a kind of design-by-committee process. One person or group wanted a certain feature, another group wanted something else, a third group though that yet another thing was important. And so on. Sorry if that sounds vague, I won't write anything more specific.
The end result was a chipset that had a lot of features. A LOT OF FEATURES. Gold plated features. But that meant higher power consumption than the competition, higher cost, larger form factor, longer time to market.
At the time, there was nobody like a Steve Jobs running Intel mobile. Nobody had the intuition and the gravitas to say: "we want A, B, C, but not D, E, F. Quit wasting time and build the fucking thing! I need something that's competitive!"
This is similar to something that an Intel chip design manager told me about 30 years ago. His view was that there were really only two ways to motivate engineers:
1) show them a path to lots and lots of money. This is the path that startups take. Focus, build something quickly, get rich or die trying.
or 2) engineers will "play in the sand", they will add in all sorts of neat features that they think are really cool, that they want to implement, that they are convinced are important. But all that crap isn't very useful to the average user, it just results in complex designs that miss their market window in so many ways.
Intel probably continued to choose path 2 for their mobile efforts.
Intel didn't fail because of any variation on The Innovator's Dilemma. They understood that mobile was the future, that it was very important. They expended tremendous amounts of capital trying to "win" in mobile. They just didn't have the organizational structure that let them execute.