because people are shitheads and can't give decent scores. just because it yanked a few threads in some miserable weeaboos heart doesn't mean it's good. Hell, look at animenfo's top 20 and tell me how many of the shows there are actually worth watching?
It's not by any means bad, but it's definitely not good. I'd rate Midori no Hibi and Welcome to the NHK as better, and a helluva lot more sad, than what this is. Also, the anime ends on a fucking happy note, so Saikano has it beat as well. Shit, even NGE trumps it.
Get over yourself, tripfag - numbers mean shit.