I use port knocking and I don’t take it seriously. Anyone using it in a serious setup is batshit. However, for fun home projects where users install that giant php based file sharing program, or that IoT camera, why not? They don’t have automated intrusion prevention, etc. They can’t understand the code to determine it’s quality, etc.

When the next 0day hits… will it be enough to protect them, yes. After all, they’re not a target and the automated attacks won’t affect them.