That's usually the belief of those who are lacking in speed and strength...not that this belief is false, but it is only part of the answer. There is a time and place for everything, and I certainly would not sacrifice training for speed and strength, only to focus on 'Internal' skills.
In my opinion, you must maximize your strengths, train for diversity of skills and be adaptable to the situation at hand. The mind, your mind is your most powerful foe and your greatest ally. Why limit yourself?
That being said, it is not practical to believe you will be good in all areas of martial arts, some of us have natural affinities to one skill set or another, a favorite technique, a weapon that feels like an extension of yourself.
I guess your path to martial truth is your own, I believe in the balance of things, the middle road, I'd rather be a Jack of all trades and a Master of none.
"if its ok for shaolin wuseng to break his vow then its ok for me to sneak behind your house at 3 in the morning and bang your dog if buddha is in your heart then its ok"-Bawang
"I get what you have said in the past, but we are not intuitive fighters. As instinctive fighters, we can chuck spears and claw and bite. We are not instinctively god at punching or kicking."-Drake
"Princess? LMAO hammer you are such a pr^t"-Frost