That's true, until you realise that most of us have a limited amount of time to dedicate to training, so if you are a person who has spent all his training time just training to lift weights, in order to be a well-rounded fighter you will have to do less weight-lifting in favour of cardio and flexibility training. I'm not denying that pure strength isn't useful to a fighter, but I see it more as a last resort kind of thing when your technique and speed doesn't work. Yes it gives you more options if you are physically stronger, but I would always put speed and technique above it when it comes to Martial Arts.