The original sin was Wickard, which found a farmer “growing wheat to feed animals on his own farm” was subject to interstate commerce “reduced the amount of wheat he would buy for animal feed on the open market, which is traded nationally, is thus interstate, and is therefore within the scope of the Commerce Clause” [1]. The court even noted that the farmer’s “relatively small amount of production of more wheat than he was allotted would not affect interstate commerce itself,” ruling that “the cumulative actions of thousands of other farmers” acting as he did would.

[1] https://en.m.wikipedia.org/wiki/Wickard_v._Filburn

This seems true… many many thousands of farmers combined consuming their own self grown wheat, would produce noticeable effects on interstate commerce. Specifically wheat markets, futures, etc…