Thanks, very interesting!
I feel like aometing like this should be provided by phoenix - it is such a basic requirement for any site. Not having this in phoenix is similar to a forum software that has no spam protection mechanisms - yes, people will use it, but they actually installed a timebomb that *will* blow up at some day.
Also the documentation about channels should cover this very important topic. You just can not put that weapon into the hands of children without protecting them :)
Thank you very much for your attention!
Have a nice day!