I don't think it's really adequate to compare the two games for raiding, tbh. In WoW it's the devs' lifeblood - they love creating them, challenging the playerbase with them, and rewarding the players for completing them. I won't say raiding is an "afterthought" in XIV like a lot of salty people like to do, but IMO it's pretty obvious that accessibility comes first to Square Enix, and hardcore raiding is the total antithesis of that.

Mythic Nighthold had about the same percentage of player clears as Gordias Savage, if that gives you an idea of the time commitment and difficulty required. Their Heroic raid clear percents are more similar to the Savage Creator level. Some of it is gear check, but some of it is just how the game is designed - tanks have a lot of small cooldowns that require resources to use but very few "big" cooldowns like Sentinel or Vengeance (to say nothing of Dead/HG lol). A spell like Cure III would be on a three-minute cooldown in WoW instead of on the global. In return, damage is still high, but less spikey, and it's more about staying ahead of the damage/outlasting the boss before he can outlast you. Classes like BRDs don't exist, so healer MP is ultra finite and they don't have too many solid oGCD emergency buttons like here.

In truth, I'd hazard that tanking and healing design in WoW is part of what makes their raids difficult. It's less about pitch-perfect lockstep mechanics and more about optimizing your throughput on your class.

Gordias was the most like a WoW Mythic insofar as how it tested your true optimization ability on your chosen job, IMO, and I think the similar clear numbers reflected that.