I agree - unless the chat is specifically for discussion of recreational substance use, I cannot understand why people bring that use into chat.
With regard specifically to medicinal mj, that area is still grey. I know some people who seem to truly benefit from medicinal mj, but they are few. I know many more people who use the term "medicinal" as a good excuse to stay stoned most of the time. The whole situation at this point is still really fuzzy.