Yep. Keep IoT on the LAN, or give it the same respect you would any other networked computer.
However, the day the the Internet Era of Fun And Games is over is the day that the internet keels over dead. The Internet was (almost literally) built on fun and games.
But the problem has been people haven't done that. So here we are.
Maybe some stick (vs carrot) for unwittingly contributing to a DDoS to make people care will work? Not sure. I'm not really liking any of these solutions, but the problem is that it'll get worse.
I don't know, do they have to run on the same network as everything else?
Maybe a first step is just to have an address range for these demonic things, which isn't publicly routable (unless you deliberating NAT it). The "home network" range (steal back some of that loopback space!).
However, the day the the Internet Era of Fun And Games is over is the day that the internet keels over dead. The Internet was (almost literally) built on fun and games.