>A negative view of Reddit as a whole makes no sense

I tend to think of "reddit" when used generally as meaning r/all for an account that isn't signed in. You won't find many "red-tribe" beliefs here, so I don't think you can say it reflects society at large. Anecdotally, I'd say the subreddit that most consistently gets something that looks a little like red tribe beliefs to the front page is r/unpopularopinion. Reddit is definitely not an even cross section of America.