David Kanter makes an excellent point about why CPUs still aren't going away any time soon - nobody's building GPUs with arbitrarily upgradeable memory, and there are still more larger-than-memory problems you want these systems to be able to tackle. As soon as your data set is too big for memory, you're basically forced to head to a CPU to coordinate things. And as big as some GPU memories have grown, the ML programming models are vastly bigger still, so there's still a lot of reasons you want a CPU in these systems.

So naturally the market is currently trying to find a middle, which is exactly where Intel's been heading if you've been paying any attention. That's the total explanation on why CPUs have been getting wider and wider - it just makes sense for them to, given the transistor budgets and the fact that just stamping more CPUs on a core is already showing signs of diminishing returns (to the point where you have to use an approach like chiplets to manage thermals appropriately, even).

The laptop market being repressed by Microsoft's stone-aged kernel CPU core management holding back designs like Lakefield (which are now completely old hat for phone-class processors) for a decade is a completely different discussion and really goes out of band with what we're talking about here though.