This will be an opinion-based response with plenty of counter views, but it goes like this:

The rotation of the mainshaft in a cone crusher is similar to (but not the same as) that of a crankshaft in an automotive application. There's plenty of "bumps and bangs" along the way with each revolution. These "bumps and bangs" could be considered similar to detonation, while the revolution itself is a smooth series of power strokes.

Retention and guidance of the shaft by itself is best suited to bushing-like confinement. A bushing with proper clearance and oil pressure is more than adequate to serve as the source of guidance and support, while being more forgiving in its willingness to accept the "bumps and bangs".

Bearings are more suitable in rotating assemblies that are not subjected to interruptions in a smooth transfer of motion. A wheel bearing, for example, has a suspension, shock absorbing device and a tire sidewall to absorb those "bumps and bangs". Bushings have their place, as do roller bearings. Rollers may be a bit too scientific for a rock crusher.

Here's my opinionated suggestion for a crusher -- hands down, a genuine Symons cone. We make parts for most all of the different crushers in the world, and we get to the bottom line the easiest, furthest and fastest with the original Symons cone crushers, for a multitude of reasons. That's an opinion that opens avenues of debate as well.

Having heard and seen all the stories, that's the view from here.