That's true; speed has different usages and aspects within itself; for now Naruto is not proficient at using it; so it is not that much of a factor in his attacks; more like it helps him avoiding several offenses. Saying he can "blitz" anyone is like saying a professional athlete can blitz anyone including professional boxers by just running at full speed. Also "blitz" means making continus high speed attacks; not a mere linear and fast attack; a slower yet unorthodox series of attacks are less predictable than a faster and linear attacks coming from a distance...