Yes, but sold only through properly licensed premises. I'd suggest chemists' shops, but, once the necessary training has been give, maybe even publicans could do it.
Another advantage might be that the strength of product sold could be held within rigid parameters. I certainly wouldn't be alone in saying that I've encountered stuff over the years that was much, much stronger than anything I'd used before. Now that's a bit scary.
So it would be manufactured by licensed factories, sold by licensed retailers and taxed. Packets would have to carry health warnings, just like cigarettes and there would be much more control over the age of people who get to buy it. Your average street dealer wouldn't give a monkey's over who he sells to, any licensed retailer would have to keep a rigid check on ages.
Another benefit is that it will go at least some way towards putting the illegal traders out of the way. Not guaranteed, of course, but many of them would just pack up.
I can't see that there is any problem with it.
Perhaps I should point out that it's about thirty years since I used any, so the Statute of Limitations must apply, surely?