1.) WAR doesn't just gain 5% damage increase while in Deliverance, it also gains access to Fell Cleave and Decimate. On top of that, you forgot the 2% Crit+ for every Abandon stack, which works up to a 10% Crit+ at 5 stacks.

2.) The reason Boris used averages as opposed to the top parses is because we currently live in the time of speed runs, any parse at the top is either extremely catered for a parse run or the time is so low that the DPS difference gets skewed depending on when the encounter ends. On top of this, any top parse will have the WAR pulling for at least 1 GCD in Defiance, which immediately puts WAR back. Regardless, don't base DPS difference on the top parses of FFLogs especially during speedrunning season.

3.) Even if every tank had equal DPS, we would still be invaluable due to SE (DPS loss not to bring us b/c now NIN needs to apply DE) and SP (insanely potent mitigation during progression). We also have the best AOE and the highest gDPS optimal opener.

4.) jsyk Maim alone gives you higher base damage than DRK or PLD, so the differences between FC/Decimate and Goring/Scourge aren't actually that far apart. On top of this you get the crit bonus from Deliverance and the insanely important advantage of being to double/triple FC inside of Berserk.

Basically. You're just not right. Even if you were right, we are close enough to the expansion where it doesn't matter.