Performing a cold water extraction or learning to make kratom tea is far less hazardous than doing something like boiling hydroiodic acid reductions or Grignards, where if you screw those up you make a hideous mess or a fire.
Doing things like cultivating opium poppies and large-scale cannabis grows are frowned upon here too, because someone caught operating a large scale grow could reasonably implicate BL in the process.
Extraction of drugs kind of implies you have the plant material or whatever in your possession anyway. And it often can remove harmful impurities (e.g. cocaine acetone washes, making DMT from acacia, etc).
Moreover, it's not like there aren't other forums out there that DO allow this kind of stuff... you just need to look around.
I'll turn the tables here: Can you come up with a reason why we should allow drug cultivation and synthesis discussion?