Carpenters are always more comfortable using dimensional lumber than sheathing lumber for attachment. In conventional construction, sheathing is unbacked except at the studs and is very flexible as a result. Over time sheathing looses it's pullout power due to this flexibility and so carpenters are very aware that nails into unbacked sheathing is an unreliable attachment. This is not the case with SIP skins, which are backed at all points and, therefore, maintain their pullout numbers indefinitely. In addition, since the fastening points are everywhere, as many fasteners as may be necessary can be put into the SIP skin.
Screws are also an option.
Another issue is pullout in osb vs plywood. Most carpenters, experienced in the osb of fifteen years ago, feel that osb has inferior sheathing characteristics to plywood, including pullout and shear characteristics. We use only APA-rated osb, which is manufactured to a higher standard than construction grade sheathing. It is a reliable, high quality product which has excellent pull out and shear strength. Essentially, when APA-rated osb is matched against plywood of the same thickness, the pullout and shear numbers are identical.