MMOs existed before DPS meters. And they were much harder than they are today. I'm also curious if this is a request in the Japanese community as well. I feel like they seem to do fine without them. (Not just this game, but in all East Asian MMOs.)

But to your point, just leveling in this game, I can tell you that it's far easier for me to tell if I or the other DPS is not playing well simply by how the dungeon is flowing. It is a lot different than dungeons in WoW or SWTOR where player power levels are absurdly high, and boss fights last about six seconds. One of the reasons I love FFXIV is that it is the closest to a traditional MMO as you will find in the West today. It takes time to get through dungeons, but if it's taking too long, the DPS is low.

Which is exactly how players used play before the GO, GO, GO gamer and the DPS meter heroes.