So no, the fact that you claim to have spent a decade professionally controlling the water temperature, bean roast,ratio, brew time & process, and grind level, does not make you any more knowledgable than any one of the other million nerds (including myself) who do this on a daily basis as well. Yes, controlling all of the variables when taste testing is obvious to most coffee geeks (people responding here). Americas test kitchen has been doing this for decades with recipes that have many more variables than the coffee brewing process.
No, those variables are probably not easily identified by the average home coffee maker. That’s because the average coffee maker is a boomer with a keurig. I still don’t think it was a particularly insightful comment though, regardless of this fact. This forum is not made of keurig drinking boomers.
It’s easy to like something though when that something’s “taste” (when drilled down into the realm of unrealities) is largely social. That’s why John Manzo noted as such in coffee, connoisseurship, and an ethnomethodologically-informed sociology of taste.
Also - is controlling the other variables actually obvious to most as you say? Are those variables even easily identified by the average home coffee maker? I'm not so sure.