Since the rpm version shipped in Fedora 10 and beyond defines a default buildroot, I think we can start phasing out the current buildroot Guideline. How about adding this to the start of the buildroot tag section?
""" === Buildroot tag === {{{admon/note|The RPM in Fedora 10 defines a default buildroot so in Fedora 10 and above it is no longer necessary to define a buildroot tag. Fedora < 10 and EPEL 5 or less still need to have the tag.}}}
[Current content remains until EPEL-5 is no longer maintained] """
https://fedoraproject.org/wiki/Phase_out_buildroot_tag_%28draft%29
-Toshio