Story mode can only be judge on your first try doing it. And i'm sure the majority wipe even on Ifrit story mode Everyone has been throw away from the ring by Titan, and i don't even speak of Garuda story mode and his little dps check with the feathers.

Just try to beat Odin and Leviathan in complete pugs team.

I think the extrem primals are well designed.

Alexander story mode is not that easy in pugs team neither. Some players just do it with a premade. What do you expect ? (schweppes !) that the boss will suddenly surprise you with a new mechanic just because you are an already well-prepared team ?
If you want to test the difficulty, don't come with your friends. And certainly not with the max ilvl gear.