Their banking on people using the RMAH, I'm not sure why that's in dispute. Your friends will get all their gear and you'll get all yours and they'll wanna move up the diffilculty and not be bothered with the constant farm so it's off to the AH. Or you have an alt you'd like to play and catch up to your buddies so its off to the real money AH. It's a tool to help do two things.
1. Generate revenue stream
2. Help casuals keep up with friends who are more hardcore.