This is great! I am glad people are able to opt out of these badge notifications… I also get them on sites I join and have become inured to them. Good catch complaining about this and also good catch getting this bug fixed. Thanks @andrei! 
On Discourse for Teams, we have disabled badges entirely because there is no need for such incentivizing on a private site for team collaboration amongst people who are already be motivated to work together!
What happens on sites with discobot disabled? Is there no way for users to opt out except by going to their user prefs?
Actually, I think this is about discouraging shoplifting!