FDR's Supreme Court blew the Commerce Clause open such that the Feds can regulate purely intrastate commerce as well.

https://en.wikipedia.org/wiki/Wickard_v._Filburn

You don't even have to participate in commerce to participate in commerce.

https://en.wikipedia.org/wiki/Gonzales_v._Raich

in Thomas' dissent in that case, he states that the decision means that the commerce clause invalidates the 10th amendment, which is huge.

It's worse than parent makes it sound: the conduct in that case was growing grain without permission, not for sale, but to feed to chickens on the same farm.

I thought that since you can nearly always draw a connection between almost any economic activity and stove kind of effect on interstate commerce, the commerce clause isn't much of a restriction these days?

Tell that to Roscoe Filburn.

Or Angel Raich! https://www.oyez.org/cases/2004/03-1454

"The question presented in this case is whether the power vested in Congress by Article I, §8, of the Constitution '[t]o make all Laws which shall be necessary and proper for carrying into Execution' its authority to 'regulate Commerce with foreign Nations, and among the several States' includes the power to prohibit the local cultivation and use of marijuana in compliance with California law." (The answer is 'yes.')