If you are talking about legalization like alcohol or tobacco, you are talking about partial legalization. Then, what you say about tax, oversight, and possibly the black market could be true, depending on how onerous the government regulations and taxes were.
On the other hand, you can brew your own beer and make adequate amounts of wine for your own consumption without tax or interference. I don't know if anyone cares if you grow and cure your own tobacco without resale, or if the personal product is palatable.
With pot, growing enough for satisfactory personal consumption is said to be easy; and the quality is probably good enough, unlike the homebrew beer I used to make. That would make many of the regulation problems you describe less onerous, and would make the appeal of black market growing drop markedly.
Small amounts of pot or alcohol for personal use is not the production of any importance and if it remained at that I suppose few agencies would devote much time and resources to stopping it. But...
the guy that is growing hundreds of plants is in it for profit like the moonshiners. And like the shiners taxes and regulation means less profit so hide it in the woods.
So large of amounts of pot will either be outlawed or regulated heavily like alcohol or not at all. I don’t see the latter happening any time soon.