Honestly, I've always found these comments a bit patronizing.
Like yeah, some people's opinions on a game change with time (I certainly changed a lot on Sun/Moon when I tried replaying them), but in most cases, people know what they like and what they don't.
I don't think people tend to do total 180s on their opinions of a game but I do think the honeymoon period is a thing. When you first play a game so long as you're liking I think most people tend to focus on the good and ignore the bad, but as time passes the initial "wow" of all the good stuff wears off and the lesser aspects may become more noticeable.
Again, not trying to say that people ever really go from loving a game to hating it, but they may be more willing to discuss any given game's faults as time goes on.