It's common knowledge, even among smokers, that it makes you a lazy bastard. Sure, maybe at first it gives you a rush, or if you do it inconsistently. But the problem is that it's addictive, so once your smoking daily it DEFINATELY interferes with your life.
Not to mention the grade of hydro that is out now, gets you so stoned you have trouble following along even a simple plot of a cartoon.
I can say that with 100% confidence because I was there at one point in my life. I feel it held me back alot, and I know alot of people who are in the same boat.
If you can make it work for you, more power to you. But for me at least, it was not productive. The thing with generalizations is, most of the time they have some truth in them.
I've had many years to think about this. It was not a hasty generalization, but a long and trying realization that brought me to the bottom of the barrell.