@daringfireball New Zealand passed this with broad support (including from Māori communities, which make the highest proportion of smokers), but a subsequent conservative government undid it.

The idea is simple: there exist adults currently who have nicotine addictions and who could not simply stop without extensive support. But smoking is obviously bad on an individual level and societal and financial level, so you phase it out.

I encourage you to read about it: https://www.sciencedirect.com/science/article/pii/S0168851024001337 For one, the fears of a black market are overblown and unsupported by evidence.