It has been remarked that you never see judo/jujutsu/aikido demonstrated full speed, or against force (or as the MMA guy puts it "active resistance"). I have explained many times that if you are unskilled at these arts you will be hurt unless you go slowly and gently. I usually get the "it does not work anyway" response.

I recently attended a self-defense seminar by a hachidan karateka (8th degree karate black belt) where he actually said "don't try to jujutsu  it, or you are going to get hurt. Jujutsu doesn't work". I had to stifle a laugh because he then proceeded to demonstrate a very poor and rough version of a beginning jujutsu kihon waza as the "better alternative".