Few things to understand here:
- Drugs are illegal in the Netherlands
- Marijuana is 'tolerated' by law enforcement, meaning it can be sold by shops, within certain rules.
- The use of drugs is not illegal per se. If someone ODs, you can call an ambulance and no questions will be asked.
- Dealing drugs (with the exception of Marijuana in regulated shops) is illegal and punishable.
As a Dutch resident, I have never understood why so many (mostly American) tourists visit The Netherlands just to use drugs in Amsterdam.
It has come to a point where cab drivers are now known to offer you drugs as soon as you arrive at the airport (this is highly illegal).
Drug tourists cause many problems and feeds the criminal system. I think it is a good thing Amsterdam is finally cracking down on drug tourism.