While paper feels very smooth to human skin, in fact it's not. If it was perfectly smooth, no pen or pencil could write on the surface (e.g.: pencil on a whiteboard).
Since the point of a pen nib is extremely small, even a small weight concentrates to that point and the nib tipping is under a lot of pressure even when you don't press while writing. As a result, when combined with the paper surface, the nib is polished slowly.
Again, this is very depending on the tipping alloy used by the manufacturer, and the result is different between manufacturers.
While paper feels very smooth to human skin, in fact it's not. If it was perfectly smooth, no pen or pencil could write on the surface (e.g.: pencil on a whiteboard).
Since the point of a pen nib is extremely small, even a small weight concentrates to that point and the nib tipping is under a lot of pressure even when you don't press while writing. As a result, when combined with the paper surface, the nib is polished slowly.
Again, this is very depending on the tipping alloy used by the manufacturer, and the result is different between manufacturers.