Lots of styles, like Wing Chun are based on timing to overcome those with great quickness. Power should be developed over time. You cannot just rely only on technique to overcome an adversary. It doesn't matter if its internal or external power it should be developed. Finally internal training is very important to your art.
All arts have it and it only comes after years of study.
Without it you are wasting your time in the arts. Traditional or modern, it doesn't matter, only that you love what you are doing and you are achieving your goals, whatever they are.