The community aspect is the fun part, really.

When you collect or farm stuff, you're often doing it with others doing the same if you do it when everyone else is (FATEs, mounts, etc)

When there is actual social content (like Field Operations or Ishgard Restoration/Cosmic Exploration), it also feels like you're doing it together compared with the solo experience that was Island Sanctuary.

When you do alliance raids, hunt trains, spawn S ranks, farm FATEs or get BLU spells on release you're doing them with lots of others as well. Same with joining map parties or raids.

Some people had an experience like that due to the Gold Saucer, Fall Guys or farming Yo-Kai FATEs in ARR. These are very early in the game and give sprouts this experience of the social aspect, which is what was always strong about the game.

And for others it's the venues or roleplaying or strong FCs.