The game emphasized SKILL; something that other MMOs simply don't do. Everything the game did at the early levels was actually a way to slowly teach you how to properly play the game. Then it started putting in "stops" to your game if you didn't understand what you were doing.
For instance, in order to reach level 20, you had to do a quest... Each class had a different quest, tailored to a play style. You had to do the quest alone and it was basically the game testing you about what you've learned; and these quests were HARD. It basically beat the skill into you. If you couldn't finish the quest, you couldn't level up anymore.
Think about any MMO out there. Would you do a pick up group? If you do, do you expect the people you find to be good? In EQ2 (at least, how it was during the first few years, I've heard they've dumbed it down since then), you could do PUGs without any issue. You knew that if someone was high level, they had the skill to get them there.