Legalisation and taxation works quite ok for alcohol and tobacco in most places. And comparatively, it works fantastically better for alcohol than the prohibition the US tried.

What's different for those other drugs? Or should we (re-) criminalise alcohol and tobacco, too?

I agree that decriminalisation is a strange halfway measure. And I can also believe that not all policy in practice is great, even if the bears the label of 'legalisation' or 'decriminalisation'.