Alan Belcher trains with his instructor, multiple time World BJJ Champion Helio Soneca.
Watch the video. What 2 positions do you see multiple times? The Rubber Guard and The Truck. In fact, the only time Belcher is able to slow Soneca down at all, even for a split second, is from the Rubber Guard or from The Truck.
Now, I'm sure Soneca doesn't call what he is doing the Rubber Guard. He has probably been doing it for a long time. But the point is that he uses the same principles to build a primary attacking style from his back.
Why would 2 practitioners with such high level ground games waste their time on movements that don't work?
And before someone says, "Belcher doesn't have high level BJJ..."
Ask Palhares.