In fact, excessive power can be detrimental, in terms of over-committing to attacks, tiring yourself out, and telegraphing your moves.
My 2c: What's excessive for one, is fine for another. I was accused of being a buffalo in a HEMA class because I hit harder than almost anyone else was comfortable with. The leader told me that he could easily counter me because my power was obviously being a buffalo and therefore would be handled by the counter-buffel moves. He was wrong.
We have a new guy in our SCA group who could give Duke Uther of the West a run for his money. He hit really hard before he learned technique. Now he hits really hard all day long.
If you train to do light power all the time, then if someone comes at you like a hurricane of control & power you stand a good chance of being his lunch.
One mans "9" is another mans "5".
PS Don't forget that Aveloc Twiceborn, who's 5'9", defeated, and rocked the world of, his Belgian 6'11" opponent at IMCF. Even after the giant picked him up and tossed him in frustration.