I don't mean any offense but disagree with that statement almost entirely. i occasionally inject something really lean like if I smoke a a bottom round or a pork loin. when i do Boston Butt I trim some of the fat away (the cap on the outer edge) and the only thing else i put on it is table salt. i lay the salt on thick sometimes i will use kosher salt if i have it but other than that i like my PP smoke and meat and let the person eating it sauce to taste. i get bark on my butt and i cannot taste the rub after 8-12 hours of cooking so why waste a nice rub on something i cannot taste anyways.
Now i will rub brisket or ribs (beef or pork) and things of that nature and i will use different rubs for different flavor profiles, but to me the rub is a flavor enhancer that is secondary to the taste of the meat and the smoke. I do use injection on something really lean for moisture but most of the time the meat i cook has plenty of marbling to maintain its own moisture.
If you like to use a complex rub on a butt or inject everything you smoke to swell like a balloon. have at it, but to me a lot of that is really over done or unnecessary.
Happy Smoking,
phatbac (Aaron)