Originally Posted by z726
A hand can grip more tightly than a vagina, though. The picture can only offer an approximation.
A while ago, there was a BBC show (I think) that showed video of intercourse from tiny cameras placed inside the vagina and on the glans of the penis. Naturally, the guy had a foreskin, but iirc there was no gliding visible from inside the vagina. I don't think everyone with a foreskin necessarily has one that's long enough, and in some cases I bet a wide glans would prevent it.
That video was probably one I saw produced by Dorling-Kindersly publishing, in case that helps you find it.