Moguls are not always made by a lot of people unintentionally skiing in the same tracks.
They are often made by the ski resort on a few trails because some people like them.

It is generally more tiring to ski through moguls, because you have to turn sharply a lot of times to avoid going straight into a mogul. That can be bad, often resulting in being out of control and not being able to slow down, or just falling when you land.