I have seen the same type of reaction since the very early stages of online gaming, such as in MUDs / MUSHs / MUx style text-based online games that started appearing in the early 90s when the internet became available for use by everyone.
There were already "roles" existing back then with tanks, healers and what they used to call "ammo" (present-day DPS). People rage-quit all the time and some people racked up reputation for being rage-quitters etc. Back then net-literacy was still in its infant stages. I recall in one game I played the game developers created humorous emotes based on some particular rage-quitters which is a problem in its own right, but the issue has existed since the dawn of online gaming.

I do visit some other places such as reddit for other games, and basically similar stories are shared of people rage-quitting, etc. I am not totally convinced this is special in FF14.
(Currently I also play EVE Online, which is filled with "mature" people who rage-quit all the time... probably because of how you can lose everything if you die in a hostile area and PKers can strip all of your belongings, etc).