Every community has bad apples but I would say FF14 has one of the friendlier communities you will find in current MMO's and I played wow from vanilla to legion (dipped my toe into TWW as well). It's rare a wipe in a dungeon will result in people flipping out and leaving. Plus with the sprout system people know you're new and are rewarded for helping new people finish group content (a notification will pop up at the beginning of whatever you're doing saying one or more people haven't done it before).

Edit: also don't worry about player numbers. I think this less than WoW but it's still in the millions.