The only real difference is personal referral, but in that case, you'd probably want to actually know the person, and not have a huge network. This plays into whatever developer review systems sites like Upwork have.
The projects you get are usually bottom of the barrel.
I have no interest in those types of projects.
It seems the idea you have is a way to pass on high-quality projects that you'd otherwise take, to someone you know and can vet. You'd likely have someone in mind already, versus having it be a huge network of other people.
Unless you wanted to hire someone who administers this group, and keeps it close-knit so that people don't dump crap projects onto good workers, or good projects to crap workers, I don't see how this can work. I don't see it as being able to grow very much besides a group of friends or former colleagues.
Not quite sure how to do that though, and if it is even possible.