If all of these fighters didn't have great ground games, they would have been submitted numerous times.
GSP is proficient in many forms of grappling. Very good wrestler. Very good BJJ fighter. Pretty simple. If not he'd look a lot like Chael Sonnen. There is takedowns in Submission Grappling though, and really the "lay and pray" REALLY originated in the ADCC type competitions. Not wrestling.
The part that gets you the pin. Wrestlers have guards. What are you even talking about? See pics below. Thats not BJJ.
Dude, give it up. He isn't going to listen. He would have you think that GSP's sick takedowns are all part of his Jiu-Jitsu training.
Wrestling is more important than bjj. That doesn't mean you can be clueless about bjj because you can't. You have to know how to stop submissions. A pure BJJ guy will beat a pure wrestler every time. That doesn't mean bjj is more important though. Not in the context of the question.