I would argue that it can be,depending on application. On a public forum dedicated to granny's knitting I can see it. On a web shop that works in a very difficult industry and has until recently required bitcoin only it makes absolutely no sense from the perspective of customer safety. Even if you live in a legal state their is a lot of money to be made from ripping your plants. These captchas collect and track us as we move throughout the web, I think the fact that this kind of tracking is brand new and possibly that many members of online cannabis communities feel safe to be members due to legalization makes us forget the very real risks both legal and non that people who grow face.