The difference is that Bob is a bot, while every avatar has a human behind them, so even silent pose jumping with a stranger can be fun.
Well, assuming they have a sense of rhythm and don`t jump across a lake and fourteen buildings to get to a new pose ... and the ones you feel are semi afk can also sod off.
I had a guy from Japan that wanted to play "Time stop" from some anime, (as in him stopping time so i would "freeze in the moment" and then he took ages to just grope me) no words, but it got me going, and i know he had fun, so yeah it happens