Uh, getting hit with a jab while coming in throws your head backwards and puts you far from a position of power to throw from. That's the entire point of the jab. It's not like everyone else just didn't like having their face touched and therefor never "ate a jab" to land on GSP.
GSP jabs perfectly, lining his arm up with his back instead of just punching frontwards. You can't walk through that kind of jab, it's your head/neck versus his entire upper body.
edit: Koscheck looks like Nogueira in that picture.