Context: this is the infamous Supreme Court case that decided the federal government has the right to regulate a farmer growing wheat for his own consumption (and, by extension, pretty much anything else it wants to), because by not buying wheat on the market he's engaging in interstate commerce.
From a European perspective, looking at this case the framing seems a bit odd. Roscoe Filburn was a commercial dairy farmer. The Wikipedia article talk about private consumption, but how can consumption inside a commercial venture (feeding the cows) be private?
If a farmer here buys fuels for their tractor, that is taxed and filed under the commercial venture of the farm. If the same farmer buys fuel for a private car, it is private consumption and taxed differently. Setting aside tax fraud, there is a very clear line between private consumption and consumption as part of the commercial venture.
Private versus public is not the important part here; interstate versus intrastate is. The US federal government was designed (via the commerce clause in the US Constitution) to be unable to regulate commerce that occurs entirely within a state, which should be entirely a matter for that state. Taken to its limit, that would mean, for instance, that federal laws about controlled substances would not apply to products produced, sold, and consumed entirely within one state, so there'd be no more ambiguity about whether the federal government can go after producers or consumers of marijuana in a state that has legalized it.
In Wickard v Filburn, the court effectively decided the federal government could regulate commerce occurring entirely within one state, on the theory that intrastate transactions could reduce interstate demand. That's an incredibly expansive and arbitrary justification, and effectively removed all limitations from the commerce clause. Invalidating that ruling would be a massive reduction in the power of the federal government to limit people's rights within a state, and an expansion of the power of individual states to make more things legal. (Note that individual states can already in general make things illegal that the federal government permits, so the primary effect of invalidating Wickard v Filburn would be to make more activities legal, rather than illegal.)
There would be a lot of fallout, and potentially a need for more targeted follow-up cases to confirm the legality of specific federal regulation that previously just relied on Wickard v Filburn; the outcome would not be 100% positive. But on balance it seems like a net positive.
The reason I mentioned private vs commercial is that the Wikipedia article (and other articles on the subject) focused on this distinction. The wheat itself was not sold and thus not commercial. The wheat never entered commerce and was consumed privately. They also describe this as farmers doing non-commercial activity.
If we do ignore that aspect, the Federal vs state regulations is the interesting aspect Wickard v. Filburn.
That factor does make the ruling in that case even more egregious, yes. Even if the court only narrowly invalidated the premise of regulating private activity that'd be a net improvement, albeit a much smaller one.
That wasn't the question. Question is if interstate commerce. If you grow a plant on your own land and sort of sell it to your own business maybe it's commerce, but only interstate by the most disingenuous stretch.
The EU equivalent would be EU constitution allowing restriction on internation commerce but then considering commerce entirely within France to be internation because hypothetically people in France might have otherwise bought from Germany.
We kind of have this kind of regulation in EU. A classic example is that commercial eggs must not be washed. This is made into an EU regulation and part of the reason for it is to enable and encourage free trade by having everyone using the same rules.
Free trade was one of the founding principles of the EU and shared regulations for food production are fairly often referenced when people discuss the pro and cons of EU membership. In some cases I have seen regulations relaxed in my own country in order to comply with the EU regulation, and at other times been made more strict, all for the goal of more trade between countries.
https://en.wikipedia.org/wiki/Wickard_v._Filburn