Toleration/decriminalisation and harm reduction policies are really important, to give you a parallel: look here at Sweden [0] that despite being really socially progressive in regards to gender and social equality still has some of the most strict drug policies in the developed world. It's not only illegal to trade drugs but also to consume them, if you are caught, for example, during a raid on a rave by the police and they test you for drugs you will get fined and can go to court for it (being imprisoned isn't happening though). You will still have a record for about 5 years even though you had no drugs in your possession. Also, needle exchange programs are fucked up as there is not national policy, it's left to the kommuner and so these programs vary wildly between cities, addicts die because of this paralysis of the system.
Portugal is the most common example of how harm reduction policies help to decrease mortality and usage, a better informed population where drugs aren't taboo makes their usage be lower and more responsible.
I have some Dutch friends, most don't really smoke weed as often, usually on a special occasion. Harder drugs usage is also more responsible, most of them test their drugs before consuming, don't overdo it. Openness and information invites responsibility.
May I suggest 'non-enforcement' as a better translation of 'gedogen'?
"Decriminalisation" is the usual term in English for the Netherlands legal policy on cannabis.
So yes, that's all anecdotal, but at least in my circles I have seen over the past 30 years that (semi)legalizing indeed helps a lot; because there is a 40-50 year trackrecord in countries like NL, there must be someone who researched it and has data about the actual effects of legalization and 'gedoog' (semi-legalization) strategies?