For tanks role you had to protect a npc while they killed mobs, dps had a time limit to kill geoups of mobs and for healers you had to keep a group alive while npcs beat groups of mobs. If ffxiv had something like this you ciuld see how well your dps/healing/tanking is without a parser and still be learning through a minigame
This exists in FFXIV. It's called Class/Job Quests and Guildhests. Unfortunately these are almost completely optional. Also you are given handicaps of Echo Buff if you fail, which is a big reason why no one takes them seriously.