It's a common sight for me if someone said FF VII is the best FF someone will whine on how overrated it is. I also see that from FF VIII as well whining on how Emo Squall is and the common offenders are the ones who like the older FF's. You can add FF X in that aswell. It's ok to criticize but to whine and bitch is a different thing.
I don't hate any FF but I dislike certain FF that's how a true fan should be.
For me this older diehard ff fans are just an elitist. it's like hearing or reading FF VII is like poison for them and can't accept that for many or for some FF VII is the best for them.
FFVII and FFVIII are very different from the previous games. In the eyes of someone that really likes the older ones, they aren't even the same series. They wouldn't like seeing those games compared to theirs. They are mostly that way due to experiences with the FFVII diehards mentioned before.
There is seriously no "true fan" though as it is all subjective.