Using CA hostname (netbios name) as CA name

On the Microsoft Technet page here: (http://technet.microsoft.com/en-us/library/cc770402.aspx) it is stated that "The CA name should not be identical to the name of the computer (NetBIOS or DNS name)." I was not aware of this guidance, and implemented a couple of CAs with the same CA name as the hostname. Why is this not a good choice? Is it simply that the CA name should be as unique as possible to avoid collision, or is there more to it than that.

Thanks