Whenever I see the name "Harry Anslinger" in this context, I am reminded that the "Emperor of Hemp", Jack Herer appears to have made up lies about him, wrote them in a book, and they have since been spread all over the internet.
The "legalize marijuana" crowd has been making stuff up for a very long time, and they also refuse to acknowledge that some people go nuts on the drug. Here's one of the latest.
http://nypost.com/2015/08/16/man-stabs-ex-girlfriend-to-death-on-sidewalk/
I don't think there's much question that Anslinger flat out lied to Congress about the intent of the Marijuana Tax Act. It was supposed to be a simple tax on production of what was then a commodity crop. When they voted on it, they didn't have any idea he was going to use it to effect a ban by refusing to issue the required tax stamps.