In the first group they've got by my rough estimate someplace around 200 million CD's sold between them ranging from metal to country. You might not be familiar with their names, but I can guarantee you've heard of the artists they've produced.
The second group is up and coming, and it doesn't surprise me you aren't familiar with them (especially as you aren't familiar with anyone in the first group.) They have produced everything from reggae to blues to metal to Christian. I strongly believe that two of them will end up with the first group within the next ten years.
OK. I went and looked up all the guys you listed and here's what I found out.
Mutt Lange: I have a (small) few albums he produced and a couple songs he wrote.
Bob Rock: I have 2 albums he produced and a couple that he mixed/engineered.
Toby Wright: I have a couple of albums that he mixed or engineered (mostly as assistant, but absolutely nothing that he produced.
Howard Benson: I have absolutely nothing by this guy.
Justin Thomas: Not having luck finding out about this guy.
Matt Squire: Have nothing by this guy either.
Rob Graves: Have nothing by this guy either.
Larry Baeder: Not finding productions that I even would have but evidently he's played guitar for a lot of established artists.
Oh. And I have more than 1200 albums which doesn't include the over 100 Gig of music on my computer.
Something tells me that in my own opinion, most of these guys haven't produced or aren't producing music I want to hear.
Oh. And just because I may have heard of some of the artists, it doesn't necessarily make them great producers. There's a lot of popular music I term crap from some very well known artists.