Your desktop? Your laptop? Whatever you happen to have running in your LAN bound to 0.0.0.0? Quite many things still assume that your local network is more trusted than the wide Internet; breaching a smart TV gives an attacker a beachhead on your local network.
> Personally I think the the idea that the LAN is some walled garden where it's fine to relax security is a bad idea.
It is a bad idea, but it happens in practice. For instance, I can vouch for the security of my desktop (except for the times I run some random development stuff bound to 0.0.0.0, for convenient multi-machine access). I can't vouch for the security of my printer, or my IoT bridge. As long as it stays true, someone breaching a single device on your LAN is already creating extra security risk for your other devices.
