I know! What I'm asking you is why not.
You haven't yet told me why I need to consider banning it to begin with.
There may be some time in the future where maybe someone markets a "make you own hash oil kit" containing a copper pipe and a can of butane. OK, I'd ban that kit.
Or they re-label an 8 oz. can of butane "Tommy Chong's Hash Gas" and sold it with instructions on how to make hash oil. I'd ban that.
Or, in my other example, I'd advocate the addition of impurities to butane. But I can't envision a scenario where I'd advocate banning butane altogether.
So to answer your question, there are better ways to solve the problem, that's why.