It's not clear how to win in Taiji PH. If you push me back but if I'm still standing on my feet, I will not say that you have just defeated me. If my hand grab on your arm, since our bodies are connected as one unit, there is no way that you can push me back without me to pull you in with me. If you pushing becomes my pulling, I don't see any win or lose there.
It's also not clear how to win in chi sao too.