As very, very well explained by Stephen Hahn recently, restricting operating system's development specific builds isn't new. In fact, it is more than desirable and as he said on his blog this can serve all of us (community users and community makers):

Certainly current distributions (or emerging ones) might consider using the stabilized build 55--however we got here--as an opportune version to base their next release upon.

Can't wait for the SX:CR build 55 to update my Solaris 11/06 systems!