Its definitely a niche game. It also has a lot of outspoken fans, as stated. I don't really believe it has quite the numbers as most "overrated" games though. On this forum, maybe. But I don't typically see it mentioned much off-site. Let alone heralded, as it is on this site

I think its just the mixture of loud adoring fans, mixed with the fact that there's not a lot of people who utterly hate it. So it balances out funny. Unlike 7 and 6 who have TONS of fans. And in 7's case, tons of haters, who are just as loud about the game, which still brings attention to it. While with 6, most people that don't like it, don't hate it, they're just generally sick of hearing about it from elitist fans. Which are probably the same sentiment of half the haters of 7. In this aspect, 9 doesn't get treated that way. Not from what I've experienced anyway