Gates of Discord. EQ back before Wow came out (9 months) MMOs were still new, servers were weak and couldn't handle the load. But the bottlenecks...

EQ was a hard game but God... Gates of Discord broke people. It was balanced to the level increase that hadn't released yet (2 expacs per year, fall expac gave levels).

The flagging mission to get into the third group zone (and to be flagged for the second raid zone) was so hard that with 5 other people who were geared in raids BEYOND the flag that you still only had about a 15% chance of victory.

The mid raid zone for the expac was the worst though. Uqua, the Ocean God's Chantry. I knew full time hard core raiders (40+ hours a week) whose bleeding edge guilds broke apart on the raid like waves against the rocks. Numerous people broke down crying in the middle and logged off never to be seen again.

They nerfed the content 3 times over 6 months and it was still BARELY beatable until the second expac and level boost.