For example, if you died, your corpse was where you died. You reappeared with literally no gear. If that was deep in a dungeon (Sebilis anyone?) then recovering it might be nontrivial. This led to corpse-run ("CR") groups. If you failed to get your corpse within a week it would disappear taking all your stuff.
You also lost XP when you died.
Another example: wood elves started in Kelethin, which was platforms in the trees with no rails. It was a rite of passage to fall off those passages and die. If you were fighting under the city at times you'd often see newbies falling to their deaths.
Travel originally was originally nontrivial too. One continent had a big city on each side (Qeynos and Freeport) and it was almost another rite of passage to do the Qeynos to Freeport run as a low-level (which could take 30-60 minutes IIRC) because you wanted to level somewhere else.
This is a genre I wish there was life in but sadly I think it's time has come and gone. A big part of what drove it was that it was the era before social networks. You met people in MMOs. Now? Everything is so results-oriented. Play a modern MMO and to do a dungeon you just queue, join, kill things off the checklist and then leave. You may never talk to anyone. People may leave mid-dungeon and get replaced without you ever noticing.
It's interesting to see how many small changes players demand ultimately kill the genre. Levelling too slow? Eliminate it. Um, what? That's half the game. Dungeon queueing. Raid queueing. Solo content, which has definite merits also means you rarely have to talk to or cooperate with anyone to get a lot of things done.