That said, this doesn't mean marijuana needs to be recreationally legalized; in the US it would only need to be made a Schedule II drug rather than a Schedule I drug. Cocaine is a Schedule II drug IIRC, and it's routinely used medically, so it doesn't make sense to have recreational legality, or tolerance of widespread use, just to get medical benefits.
For virtually every cause, there are groups "working heavily behind the scenes for decades" -- the existence of activist pressure doesn't seem to correlate with policy change. I'd love to see hard data disagreeing with me, but this is my impression from being an activist for some time, and knowing the histories of social change for various struggles.