Despite the fact that it's been talked about several times here, I still see some people disagreeing with it as if it doesn't really matter. Some people think that if you are just good with your trading strategy, you can begin to make profits, which I usually disagree with. There is every possibility that a trader can have a good strategy, but perhaps since we don't usually know the market direction, if a trader who doesn't have a good ability to control their emotions encounters losses, could they be able to bear the loss? Some traders will not, and that's not a good characteristic for a real trader. So, I agree with you.
How will you even encounter a loss if you already have a good strategy in place? A good strategy always have an exit plan that makes sure your losses are at a minimum, what I think someone should have instead of emotional control when it comes to trading is discipline, discipline encompasses even that part so having a discipline means you have control over more fundamental things granted you have a good trading strategy in place.