But currently the federal government can still come in and make arrests, although they typically choose not to enforce the law, because doing so would be politically unpopular. Plus it's not like there are FBI agents walking the beat trying to make low-level drug busts.
The most confusing is Washington D.C., a federal territory, which has been granted limited home rule. They voted in a referendum to legalize and regulate marijuana, but then were prohibited by Congress from spending any money to actually draft the necessary regulations. The result is that marijuana is illegal to buy or sell but legal to possess or use, except in many public parks which are technically part of the federal National Park system.
There are "dry counties" in the US today, so local jurisdictions can do this. (Note that most local jurisdictions become "dry" after 2am, anyhow.)
As an outside observer with an interest (but no formal education!) I find U.S. state/federal laws really confusing, and I'm sure I have all of the above mixed up. Would love to hear you expand your comment with some examples of how the constitutional protections are different now compared to then, and as you say watered down.