XP parties were fun in XI. Were they more social than FFXIV's FATE parties ?... Dunno, I feel like the communities are completely different but I stopped FFXI when Wings of the Goddess came out so it may have changed after that.

Yes we waited hours to get that last member we needed to camp Crawler's Nest, hours running in circles in Jeuno, playing dice... but what do we do today ? Waiting 30+ min to get in queue to speedrun a dungeon, hoping secretly to avoid the "first timers" so we can speedrun even more. Rinse & repeat.

The real pain was standing on the same spot for hours because all others good spots were taken, or if we moved too far we could be "ambushed", killed and lose that precious XP.
Who never dreaded the night in Valkurm Dunes when we could read the despair, the fear, the hatred all summed up in one word : "BOGYYYY !!!"

The closest we get in FF14 would be the FATE parties, where everyone minds their own business, no need for a balanced group, everyone can go as PLD if they feel like it. The only FATEs so far to require a bit of teamwork would be Cancer, Gorgimera, Odin & Behemot. 4 out of hundreds...

So yeah, EXP parties might be a good 3rd way to lvl up and to actually learn to play your Job (not sure players really use Leves to lvl up but I could be wrong). And you would meet people of your server
Of course, that would need to be changed to fit FFXIV. Grinding on 300xp worth monsters might kill anybody's sanity