I disagree with that. It may be partly true on faster or stained water. Yet, go fish a gin clear spring creek with wary trout that have all the time in the world to inspect your bug before they eat. I've seen them refuse naturals of various species offering a preference for a female PED over a male.
As far as the original topic, if you have an idea of the forage base, baitfish, bluegills, sunfish, crappie, and such, you have a head start in determining major factors. If they're keying on 4" shad, I'm not going to be fishing a black/blue jig. Matching the hatch, in bass fishing terms, would be more closely associated with establishing a pattern.