Use a bitcoin like blockchain for validation and/or prevent attacker success?
That presumes the basic IoT firmware actually works. Most breaks are due to either buggy local firmware (in the IoT device) or buggy firmware or wetware somewhere upstream (like the cloud where the access credentials for the IoT are stored, administered by harpoon susceptible meatbags).
If the "given" part of the article is true (the free "no-IP needed" firmware is everywhere 100% bug free in a security sense) then using a blockchain thingy may be useful. Otherwise, I am just not seeing why every IoT device needs the power to do the work to support the blockchain idea. There might be marginal utility as a whole house gateway to the home's IoT heap.