Besides being the best leveling option at the moment (esp. for second/third/... classes) FATEs are also the most inclusive content the game has to offer.

FATE groups can be pretty much build however you want, there is no need for dedicated tanks/healers. I've had groups with 4 healers and 4 DPS, 3 Tanks/3Healers/2DPS, and every possible composition you can think of. The levelranges are quite forgiving, more often then not you will see almost ~10 levels difference between the lowest and highest member of a group. They offer an option to do it as long as you want. You have half an hour? No problem, say "bye" once you have to go, no one is going to be mad and the spot will be filled up in no time. And even if no replacement is found directly you can go on with fewer people without a problem.

These things and the fact, that you are not able to influence the speed at which you can progress (no "go go go" shouting to tell the tank to pull more and faster), and that there is no clear goal (no "ololol gimme them lootz from da bozz speedrunning") make FATE farming in groups one of the friendliest, socially inclusive and overall nicest experiences i have found in the game. The "forced" breaks while waiting for new FATES to spawn is often a good time to actually chat with the people you are with, and make friends outside your already established FC circle.

so for all the bad things FATEs have, they at least can offer some positives besides being the "pure grindfests" a lot of people make them out to be.