I don't know where you're getting your info, but Hi-lo is quite good for single deck. It's not the best, but it's still very good. Probably the best betting correlation of any count.
You seem to be talking about the importance of playing decisions, which I wasn't really discussing. Playing decisions just aren't that important, even if you memorize the whole deck. You make money in this game by betting when the blackjacks are on the way, not by knowing when to stand on soft 17 vs. a nine.