[CentOS] What's wrong with yum-priorities?

"The upstream maintainer of yum, Seth Vidal, had the following to say
about 'yum priorities' in September 2009:

Gosh, I hope people do not set up yum priorities. There are so many things
about priorities that make me cringe all over. It could just be that it
reminds me of apt 'pinning' and that makes me want to hurl."

This note was placed on the wiki (PackageManagement/Yum?Priorities)
without any explanation why yum-priorities isn't a good idea.

yum-priorities doesn't appear in RHEL 5.4 but protectbase does. Is that
the better choice and if so why?

Thanks,

Dennisk

-- 
"Free as in Freedom"
Free Software Foundation