I mean... I'm a WoW player who stayed. You can push forward this notion all you'd like, but the numbers show the facts here. Alls I see are people defending ARR like it's just fine and not an issue. While the game continues to hemorrhage people across the board. The toxic positivity is as bad in XIV community as the toxic negativity is in WoW. There is no balance, and the 'everything is just fine' thing regarding the story is that one dog sitting in a burning house meme 'this is fine'.
Thing is, I don't introduce WoW players. I introduced my siblings and friends who had never touched MMORPGs before. So your 'speculation' goes out of the window right there. They didn't have any predetermined notions of the game.
And at the end of the day, regardless, a new player to FFXIV is a new player to FFXIV. New to the genre or not. If they played WoW or not really shouldn't make their feedback any less valuable. As... again, WoW is a competitor, as it should be, and different perspectives are a good thing even if you disagree. At the moment, the state of FFXIV clearly shows it's needing to improve. People are sharing their grievances. I don't agree with the toxicity in WoW, but I don't like the 'everything is fine' thing FFXIV seems to have (which is clearly wrong - factually, given numbers, even).