In Raich, there's two things going on -- separate, but related. One, Congress is using the power of the Commerce Clause to regulate interstate commerce. In this case, Congress is prohibiting the interstate commerce of marijuana. That's all the Commerce Clause allows -- interstate regulation only.
Two, in order for Congress to effectively regulate interstate marijuana, Congress uses the power of the Necessary and Proper Clause to write legislation. In this case, the legislation prohibits the in-state growing, possessing and distribution of marijuana -- recreational OR medical.
How can Congress do this? The only way they can do this is if they can prove to the courts that a) locally grown marijuana has a substantial effect on Congress' efforts to regulate interstate marijuana and b) the legislation is both necessary and proper to stop this activity.
The government has never claimed that Raich's marijuana is interstate or even commerce. Like I said, it doesn't have to be. It is an activity that, when combined with others doing the same thing, has a substantial effect on Congress' ability to execute their regulations.
Which, taken together means that all that is necessary for Congress to increase it's power is for them to craft legislation so ill-conceived and badly written that it's unenforceable without it. We don't need no steenkin' amendment.