Also the stability of updates doesn't even come into it, not every distro aims to be rock stable. But at the very least a RR should contain all packages needed to built a distro and have them roll in some manner, and Tumbleweed just doesn't. It doesn't even contain packages intended for the next Suse version, that's factory. Which is also why you can't remove your current 13.1 repositories when using it. Cause that's where most of your packages come from.
Calling a package repository like Tumbleweed a RR distro, or even just a distro, is just plain rude to all the people doing work on actual distros. Cause there is more to running a distro than updating a few packages.