This is an absolutely ridiculous sentiment because it asserts that anybody who hasn't played the games prior has no right to make any comment other than a positive one lest it's 'trolling'. Kingdom Hearts 3 is, when push comes to shove, a Disney game, and there will be younger people who weren't even playing video games when KH1 and KH2 came out who might be tempted to pick it up because Big Hero Six or Tangled are in the advertising for it. This is the same fringe audience that made KH1 such a hit, incidentally - it wasn't just the FF audience buying it, but the FF audience combined with a demographic who never usually would buy this type of game, but did because Disney.
Anyway, telling that audience they need to play eight other games first is ridiculous, and if that's really the case, that's a failing. Even Mass Effect, a complicated narrative-driven series where your saves actively carry over, took massive steps each game to ensure newcomers wouldn't be alienated. There is no excuse. In this instance, it's totally possible to find a balance.
KH2 found that balance fairly well, I think, btw. The Roxas stuff in the opening is surprisingly deft, because it at once is feeding intriguing information to those who did play COM, while those who played KH1 but skipped it are left curious about what's going on and where Sora is - and finally, for newcomers, the Roxas section acts as a leisurely-paced tutorial, as Destiny Islands did. It has a triple purpose, it's very cleverly designed. KH3 just has no idea tho.
