That chart was all shades wrong. No Dragoon would ever be top DPS because the vast majority of them of them would be on the ground... dead.

Initially, the developers think within their own little box, which is why developers will get surprised when players use classes in a manner that they did not expect. It happens (had happened & will continue to happen) in MMOs plenty of times. So, when that happens, they go back and recreate it, even creating ideal scenarios for that happens, and they base their findings off of that.

Then classes get tweaked, players adapt to the changes or move on to the next Face Roll Class.