My 5.5m Northcraft with Suzuki 100 2-stroke easily pulls 2 skiers out, or a deep water mono start. Often have 5 on board and 1 in the water with no problems at all.
It's not such an issue with larger craft, but smaller hardboats (closed bow) can have difficulty getting onto the plane pulling a skier (especially off a ski pole) as the stern tends to bury itself. This can be overcome easily on a rib by moving some of the weight (crew, fuel, etc.) towards the bow.
IMO ribs are much more versatile all round than hardboats and pulling skiers is certainly no exception to this.