I believe they mean in the useless way, where you had limited if any slots in a group making gameplay frustrating. To be fair, this was semi-intentional in EQ so they prolly just brought it over and thought it would work again, but player expectations were growing at this point and another EQ had to provide more than just a big world and fancy graphics (which honestly, I'd argue the graphical direction they took in 2004 also hurt them)
One was shaman, because their wards did not take mitigation into account. It was in fact quite unpleasant. Sitting around waiting for power after one fight because your signature spells weren't worth much. LU13 fixed this thankfully. They reigned in some healing classes and upped others and it was seriously needed.
Shaman comes to mind for me, because I tried to play one. Their core feature, wards, simply did not work as it was designed. They prevented virtually no damage and were high cost, due to them not taking mitigation into account. As a signature feature of the class, and with content tuned to rely on signature heals in group content, shamans were totally pointless for a long time.