Encrypting a password is a bad idea. People still do it. People will ask about it on SO. They will (hopefully get an answer telling them why it's a bad idea).
So all in all, I think that the existence of this tag is better than the alternative (which is that there will still be questions about the topic, but they can't easily be identified).
But, the tag wiki (and it's summary) of password-encryption is ... lacking, to be honest. I think this tag could really profit from a well-written summary of the issues of this topic (and ideally a prototypical question/answer "How do I encrypt my passwords?").