If you place the turbine above the tower, "kind of like a tall crown", there can only be one point of contact - the bearing on which it sits.

Note that every point of contact between the tower and turbine must be rotational. You can't have multiple mounts for the turbine at the top of the tower, because then they're not axial. If they're not axial and they're fixed, they freeze the turbine. If they're not fixed, they're not the point of contact, whatever axially-mounted bearing they're on is.

Of course, that's a completely different scenario to "the shaft doesn't have to be completely surrounded at ground level by the turbine" - which is true, but not doing so reduces your swept area and thus, the amount of power you generate.

You could put the turbine partway up the shaft, so that it sticks up - but like putting it entirely above the shaft, you're going to get a bending force from the section above the tower. It might not be as damaging because you can have more bearings (thus, points of contact) along the section that is below the top of the tower, but it's still going to be harder on the components (and probably even less efficient as the force exerted will press the bearings together harder on one side, increasing friction).