EasyBib, RefME, and other bibliography creation tools over the years. The reader seemed to take most offense to my recent post about Google Docs Add-ons in which I included the EasyBib Add-on. The reader rightly pointed out that those tools don't always format citations perfectly.
Granted those tools aren't always perfect in their formatting of citations (I have pointed out some of those flaws in my webinars and workshops over the years), but I think they are still valuable because they help get students into the habit of citing their sources of information and keeping a record of the sources they use. Furthermore, if EasyBib, RefME, or one of the other bibliography generators does make a mistake you can turn that into a teaching opportunity with your students. Point out the flaw and how to correct it.
Finally, we can tell students not to use bibliography creation tools but they are going to find them and try to use them anyway. The same can be said for Wikipedia, but that's a conversation for another day. I would rather tell students about bibliography creation tools and teach them how to recognize if the tool made an error than I would pretend that students aren't going to use the tools.