You're correct, though I'd push back a bit on "all kinds of chemicals and additives".
They do use them: sulfites for preservation, fining agents for clarity, yeast energizers, acids and bases. But the way you phrase it, it sounds like they're making pop-tarts or chewing gum. A lot of these additives are used even by fine winemakers. Even French winemakers, who have a whole host of rules they have to follow.
Still, I'm picking on your phraseology, but not disagreeing with your point. Modern winemaking is all about control, which produces consistently good but rarely great wines. More expensive wines are more expensive in part because they risk failure -- though few take enough risks to produce a truly undrinkable wine these days.
There's nothing wrong with those "good" wines, though I'm puzzled about the cheap supermarket wine winning a contest. Cheap supermarket wines are entirely drinkable but don't even try to have the qualities that win any genuine prizes. It doesn't take a sommelier to notice that; it tastes like every other wine. Contests usually reward what stands out.
Perhaps some fine winemaker sold off surplus stock. It happens; they have a good year and don't want to dilute the value of their prize brand.
These stories keep coming up about how wine judges are easily duped, and indeed, there is plenty of chicanery surrounding wine ratings. There is a lot of snobbery, and a lot of envy around that snobbery. But there's no reason to pay a lot for a wine unless you've gotten bored with ordinary table wine.