It was more at the endgame level. You HAD to have a certain item to be accepted to the highest level HNMs, especially if you were on a common job that the group only needed one of.

Take THF. It wasn't that you needed leaping boots at level 75. They were obsolete by 72. No, if you wanted to join an HNM shell, you needed Treasure Hunter 4. You needed the relic gloves, the knife, the artifact boots, etc. A THF4 thief would get a guaranteed spot in the alliance, in order to tag the mob and then otherwise do hate control. (Sometimes they'd get rotated out after tagging the mob, depending on the DPS checks on the fight.) But the alliance ONLY needed one, and a TH3 thief was less desired.

With the healers it was less fussy, but if you had a RDM who had obtained the relic hat and Dalmatica vs a red mage who had not, and they were both applying for the HNM's open red mage slot, guess which one they'd pick?