It's because growers and smokers use the term 'phenotype' wrong. A phenotype is just a singular genetic aspect of an organism. Take humans for example. Hair can present multiple phenotypic expressions - color, length, density, curvature, angle at which it leaves the head, etc. You don't say a red-head has a "redhead pheno", because the color red is but one "pheno". You can be red curly, red straight, red dense, red thin, red wavy, red long, red short, darker or lighter red, etc. And you can definitely not say that just because you knew a hot red hot in high school, that hotness has anything to do with red head. You didn't know the "red pheno" because you knew a hot redhead. You knew a girl with 1,000 phenotypic expressions that made her beautiful (nose, face, size, bone structure, on and on and on).
Same with cannabis. I see alot of people say things like "I got the purple pheno, it really packs a punch", which makes no sense. You're talking about two phenotypic expressions - potency, and color. Wedding cake isn't a single pheno. It's an individual. Like a single brother out of a family that has 1,000 children, no other child will be exactly like it because of the 1,000,000 phenotypic expressions that make an individual unique. Maybe another sibling has a similar trait, but that doesn't mean it's the same "pheno". You might get another sibling that has a similar color and bud structure to the clone-only wedding cake, but it doesn't have the same terpene or cannabinoid profile. You might get one with a knock-out buzz, but without the bud structure and yield. We really need to move away from grouping dozens of phenotypic expressions of an individual into the term "pheno".