Nobody is suggesting that a fire investigator needs to remember everything, just the basics. The list of 16 is certainly redundant, and 1033 says that the knowledge you need is in 921, so if it's not in 921, that's beyond the scope of 1033's requirements. On the other hand, the heat release rate of a fire is measured in kilowatts or megawatts. If you don't know what a watt is, you are unqualified. Fire is a chemical reaction. If you can't describe the simplest chemical reaction involving combustion, you are unqualified. If you can't describe the difference between energy and power, you are unqualified. 1033 says so.

A fire investigator who can't define basic terms (not verbatim from NFPA 921, just a correct definition) is like an engineer who doesn't know physics, or a chemist who doesn't know chemistry, or a carpenter who does not know how big an inch is.

My question is why should fire investigators be allowed to affect someone's life if they can't demonstrate a basic knowledge of fire behavior.