That's not my experience; plenty of productive artists (musicians, actors and photographers) among the smokers I know.
Some have spoken highly of brainstorming while stoned, fleshing out the details and narrowing their scope and intentions as they sober up, while others say that it helps them concentrate by slowing down their racing thoughts.
And while I've known people who've used it to waste their lives away, that's true of so many things.
But that doesn't mean every thought is going to be valuable, or even good. If treated that way, I think it can be a good tool. I am thankfully not prone to addiction or reliance.
It reminds me of Carl Sagan's thoughts [0] and especially this quote:
> If I find in the morning a message from myself the night before informing me that there is a world around us which we barely sense, or that we can become one with the universe, or even that certain politicians are desperately frightened men, I may tend to disbelieve; but when I’m high I know about this disbelief. And so I have a tape in which I exhort myself to take such remarks seriously. I say ‘Listen closely, you sonofabitch of the morning! This stuff is real!’
I find it more fascinating to explore thought while on cannabis and that is what I primarily use it for. Instead of saying "dude you're so high" to a far out thought, I try to explore it as far as it will go. Quite enjoyable.