Above all, how this was legal in Japan until very recently is beyond me. I thought Japan has strict gun controls in place.
Edit: Apparently coilguns are categorized as firearms, which is illegal today, if they're lethal enough.
A "good" way for authorities to show how they are on top of this and that you shouldn't share videos on coil guns on the internet. Seems a bit authoritarian.
It is about the accuracy and how fast can the other person react or protect themselves. I would say that guns like these exceed the throwing of rock with high numbers. You can also do it many times in a short duration.
Fireguns are effective for that particular reason. They are accurate, and there is no way to protect against, as they are very fast to use. And you are not limited to single throw.
A 95 MPH fastball which can seriously hurt has about 150J worth of energy. Meanwhile a professionally made coil gun using a lot more capacitors hit 10J and this isn’t nearly as powerful. https://en.wikipedia.org/wiki/GR-1_%22Anvil%22