They aren't really having "major" problems. No terrible engineering or egregious decisions, it's just a less competitive space than mobile. They aren't excelling, but they are still ahead of AMD in many ways (with key obvious exceptions like graphics focus, core count).
We can talk about process and transistor density, and you might hear that intel is struggling here, but I'm skeptical about this, as there is some leeway/play here in how companies measure process and transistor density against each other.
I think the big problem isn't so much Intel themselves as it is x86 being long in the tooth. It's Intels bread and butter, but it seems kinda fucked per-watt vs ARM long/medium term. Not really Intels fault, except that their wagon is hitched to that star.
Mobile has been selling more than traditional x86 machines for a while now, so the money and the will just isn't there like it once was to spur progress, at least proportionately that is, in comparison to mobile.
So really it's not so much Intel sucking too much, but instead the mobile/ARM market just being more relevant, and more fiercely competitive, with almost impossible year on year performance improvements.
Intel looks bad in comparison to this, sure. Do they look bad in a vacuum or VS their former Intel selves ?... not so much. Doesn't mean they shouldn't be worried about their lunch getting eaten though.