Words have meanings. Growing wheat for private consumption on one's own land is not "commerce" whatever the honourable idiots of the US Supreme Court think.
For a modern example, if 1 million people in Florida install solar panels on their roofs it's going to defacto alter the wholesale electricity market.
Now, if that impact is enough to justify regulation is another issue, but the impact is clearly there.
Again, the regulation was he could use up to 11.1 acres and he did around twice that which is significant.