Just like I people are using it incorrectly and creating and changing definitions on this forum for not knowing better, it is how it became rampid and wrong and past games of the same people.

Many times especially before WOOW and newer games it was always DD for a class designated for damage dealing. DPS was properly used as your output or gear relation.

DPS is wrong, nad so are those who adopted it wrong, but it ended up being adopted because many people are stuck in using it wrong.