Why haven't more countries taken up the Dutch method of tolerating illegal cannabis use?

First off, cannabis IS illegal in the Netherlands (in contrast to what many ppl might make you believe). The fact is that the police their tolerate it anyway. The idea behind this is that by giving people the ability to smoke marijuana, it will make them crave other more problematic drugs like cocaine and heroin less. Evidently, the practice has worked since the use of "hard drugs" has gone down since cannabis became tolerable. Well, if this practice truly does keep people from using more troublesome drugs, why dont more countries take up this method of tolerating cannabis?