When platforms failed to come together because Intel was not delivering the goods, Nokia had to scramble to get new phones ramped up around alternative platforms. Nokia lost a lot of valuable time this way right when Apple and Android started kicking its ass. I wouldn't point at it as the root cause for Nokia's rapid collapse but it certainly was a contributing factor. E.g. Meego was years late to the market partly because of this and ultimately killed off in favor of the deal with Microsoft (another ill fated bet). And yes, Intel Atom was a big part of that failing as well.
Bottom line is that Intel tried and failed to get into the mobile market repeatedly and failed while being way too comfortable milking desktops and servers. Now that that market finally seems to be drying up, they have a problem and still no viable strategy to deal with it. Atom flopped. Itanium flopped. AMD is back looking stronger than ever. MS is has retired the wintel brand years ago and is seemingly open to running on ARM and getting quite cozy with Linux. Apple is widely rumored to also consider switching to their quite credible in house ARM based processors.