It's definitely not a baseless stereotype, but then again few truly are. It is however a stereotype that is pretty inaccurate and more readily accepted than it should be.

Your last statement alludes to other related stereotypes; that people who smoke cannabis are the kind of people who make this argument, or that people who smoke cannabis secretly only want to legalise it for the sake of their personal weed-greed.

This isn't targeted at you, I'm not saying that you believe these things.

In terms of anonymity though, there'd have to be a lot of people buying your paper to avoid uniqueness any individual document. Maybe you could buy, rebrand and resell the most commonly sold yellow paper as 'Super Secret Document Paper'!