It can be just minimum level of items equipped calculation (remember level 5 storyline quest? equip level 5 head, top, bottom, gloves and boots, as i remember.)
Pro tip: Trade in Tombstone of Philosophy for 1 Dark Light Accessory and wear an unfinished Relic weapon: instant i60 average! Switch to all crafting gear when you get in for maximum spiritbinding profit!
yeah jewelry is an issue IMO, some 55 HQ crafted is better than dark light when materia slotted properly.
Jewelry might not even factor in, or might be weighed much lower. People spiritbonding crafting gear (making the slot essentially empty) is testament to the fact that it doesn't have as much weight as the community likes to think.
Just because SE might set the requirements low, doesn't mean a full group with the bare minimum would be able to down it. Not as a pug anyways. World class players will always down content with minimal gear, and I can guarantee you won't be playing with them in duty finder nor a pug you may join in Mor Dhona.
So yes, gear discrimination will still be 100% justifiable, as the people who set those standards understand that you can't kill bosses with happiness and friendship alone.