Actually, no.
That's like saying "So many people think Arabs are terrorists, so they are", "Mexicans are all lazy", or "Jewish people just want $$$"
Definitely not true. It's because of how people have been told to look at marijuana without even bothering to try it themselves to see if it's true. Some people even compare marijuana to cocaine and heroine, when it's really not like that at all. Drug dealers don't even view marijuana as a drug and neither do the people imprisoned for cocaine possession.
Cigarettes are more harmful than marijuana. Some people believe one joint = 15 cigarettes, but as I mentioned before, that's only possible if you really, really cake in the tobacco. Otherwise, it's relatively harmless, especially if you ingest it, say, in a brownie. Then your lungs definitely won't be affected, and nei' your stomach.
When I was growing up, movies, television, and people told me marijuana was a dangerous drug that caused people to become violent. Is that true? No. Quite the contrary. The only reason so many people think it's a bad drug is because it's set up to look that way, so a crapload of people will oppose it if ever people were to band together and try to appeal the ban on weed. If people think marijuana is the same or worse than cocaine, and makes people violent, they're less likely to want it legalized, and then the paper and clothing companies won't be at risk.
See?