We have nice mods who totally don't abuse their powers to ban all those who criticize the site in the slightest :p (except maybe Fizz don't trust him)
That said, I'd like to point out that the 99% comment is kinda obscure as it is. It's not like PM has a huge banner where he boasts about having near perfect accuracy. And he does attempt to fix it, as seen by the other meta posts he makes for us to answer any time we notice an error, and to be fair, they're generally fixed.
This is not his main job, and he can only invest as much time in it as he sees fit. Any omission is not due to deliberate negligence, not does he intend to spread false information. He does his best, and that's quite enough for most of us, who are casual users of the site.
That said, you do have to admit that the question you referenced was kinda open ended, asked more to satisfy some curiosity than to actually use. It was a question that relied on the use of statistics and not user experience and guidance, nor had an answer that was useful for the vast majority of the people who use the site. While your complaint may be valid, the scope and context are really narrow: the site offers more than that, and for the most part, it's accurate and serves the purpose. Most folks want to play a game and have fun, not overanalyze the data involved in the game.