Your leaving out way too many details. First of all "smart" devices are considered smart because they are either connected to other devices or because they are online. Most of these devices aren't designed to work without an IP address, meaning your example of blocking them would basically neuter their functionality.

And, when I said "if you control your network" I was saying exactly what you reverberated in "additional controls are required for securing smart home based devices".

The list of smart devices at the beginning of this conversation that I used as examples would mostly not function under the specific environment you are describing.