Go on FFLogs and look at the usage statistics for PLD throughout Midas and Creator. There were as many, and often more Paladins clearing the first three fights in each of those two tiers than there were Dark Knights, and the story is similar through most/all of the HW primals.

Paladin was only excluded at the high end, for groups doing speedruns. SB DRK is only doing marginally better in that regard than HW PLD was, except that HW PLD was useful and popular at the lower end. DRK is underperforming at all levels.