Part of the reason you make it more accessible is knowing how people use it, and to try to get people to do the less harmful thing in a class of things. So, you know, try to steer people to cocaine and way from meth while recognizing that cocaine isn't alcohol or weed or caffeine.
On the other hand, you probably want anything involving needles to be administered by a nurse. Opiate pills after surgery? Prescription so you'll have enough.
If getting low to moderate level drugs made more sense, why bother with the real hard stuff?
Someone wanting a couple vicodin might be happy to have that option, perhaps with the occasional oxy, and never approach Fentnyl, heroin.
Think of it like a sort of diversion. We know people will do it, and they have human reasons for it too. Copping a buzz isn't any real crime, and people know that.
The way it is now is misaligned with those basic realities. People are at odds with the whole thing, incentives are wrong, risks too high, costs too high, it's just a mess.
So, we enable them to do it and build in friction where there should be some to keep the masses in a reasonable zone where they can just be humans doing things humans do.