The "rules" I speak of, are the same rules that aren't written anywhere, but we are meant to follow them. The untold rules of RDF, which, I assume, are applied to PUG's to some degree.
Why would you allow only Retri to roll leather belt (beyond leather classes), and say no to hunter, warrior, enha shaman? Agi, crit, arp, sounds like a dream item for a Warrior. Would you allow Druids, Shamans and Holy Paladins to roll lower armor tier items? Cloth users sure are thrilled. How would that be fair, you'd still let Retri roll a leather belt? This is why there shouldn't be exceptions, if one exception is made, why few others can't be made too? Or is it just convenient for you (not you specifically) to say who can roll what. I'd imagine the staff do apply some RDF ninja rules when dealing with some PUG ninja reports. This is why, IMHO, whatever are the rules of RDF rolls, should apply generally to PUG's. RL's are the ones who then can make the specific rulings (BoE reserve, No DBW for Retris, but they can roll PP leather belt).
Anybody can make a BiS list and post it on the forum. Fury with a staff? BiS list coming right up. Melee Frost Mage? Glad you asked!
There are BiS lists for Full STR Paladin, as well as Agiladin. Do you ever specify which BiS list you're going for when joining a PUG? Exactly. 2p, 4p Assassination/Combat? Or just conveniently switch the list, if more items drops for other set? Or roll for both? Nobody asked anyway.