A pointless distinction to make.
Gul'dan technically wasn't the "final boss" in gameplay sense, but he was still the final villain of the story, replacing Grommash/Iron Horde after 6.1. Archimonde wasn't even a character in WoD, he appeared for 2 minutes, got his hooves stabbed by the players, and died. Gul'dan was pretty much the final villain.
Turalyon is just a meme answer from the vocal minority of Horde players that still hasn't gotten over SoO. Odyn also seems like a meme answer, he was on good terms with the champions in Legion.
That you brought up 11.0 is irrelevant to me as I wasn't talking about it.
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Yeah... it's literally just some Horde diehard fanboys online that are still salty about SoO.
You'd think they would give up after Blizzard repeated SoO with Battle of Dazar'alor, but nope! They do not desist in their wishes to see an Alliance city turned into a raid. It's not happening.