Theory isn't bad, but too much isn't good either. Things tend to not work out as planned. For example, look at Durant: It is a 70 HP basic pokemon that has zero offensive presence and wins by discarding 4 cards per turn. It might be able to boost it's HP to 100 through Special Metal and Eviolite. When facing a 60 card deck it seems impossible to win because all your opponent has to do is kill 6 of those things. But as it turns out it works. Theoretically Durant shouldn't be a deck, much less win tournaments, but somehow it does.