The traction on a flt belt and a crowned pulley has to be controlled and also that there will be wear, and thus a slicking or shining of the surface of the belt and the pulley, but obviously the belt carrying the majority of the wear and becoming slick. Which only exacerbates the problems, and can eve change the patterns of the different motional/loading components of the relationships.
Thus the lowest level of wow and flutter and thd, etc, will come about with a certain level of loading of the system, which is carefully adjusted by the given designers of said system. Overall, the system is more complex than it initially looks. The belts are allowed wear range and the distances and and tension(s) between components are carefully adjusted. Certain derometers and constitution of the rubber belt and so on, are carefully selected.
For example, with a crowned pulley, a certain scalloped or hollowed out characteristic of a belt cross sectional profile might work better than a purely flat belt. More perfected speed, lower wear? Depends.
While just any combination of these parts will make for a minimal ’turntable’, best results are invariably down the complex analysis path.
This is why for example, with a Linn LP12..there is only one real choice regarding getting what you are paying for, and that is to use a Linn sourced belt.
This is getting into the nitty gritty of it, though, so one’s own priorities and limits in involvement is the deal. As per norm.