I'd say it isn't just because I've never heard of anyone talk about it in like a decade. Movies like The Exorcist, The Shining and Psycho I hear people talk about a lot to this day and is always in the discussion of classic horror. I've never heard anyone bring up Blair Witch ever in classic movie discussions. Not to say it didn't impact the genre or the post-2000 hand held film phenomenon, but that's about it. There's been much better scary movies done since then with the same found footage gimmick (paranormal activity) imo which is why it never aged well to begin with.
Agree to disagree breh. I think it's a classic and I don't think it gets the love it deserves because a lot of horror buffs revolt against found footage therefore they'll revolt against that flick which kicked off the current craze. It stayed with me though because there are trees in my backyard and there used to be A LOT more than there are now and let's just say that wasn't fun coming home after the movie