@PaulHoule those are some good points. I would've agreed up until recently, but the newer IoT mesh radios have gotten surprisingly robust. The frequency modulators and collision detection baked into the last few iterations of lower cost IoT chips (like DigiMesh/Nordic chips) really have improved. We've been using DigiMesh 900 MHz units in a greenhouse setting with great success (especially compared to 2.4GHz which drops packets with abandon), with no measured packet loss to date. Pretty sweet!
To wrap that up, low-throughput but hi-scalability mesh networks combined with better firmware, network configuration, tuned mesh protocols, and proper software support to make the "throw a few of these down and forget them" scenario a real possibility. Check out the Beep networks blog for a longer explanation: http://blog.beepnetworks.com/2016/09/messy-networks-for-the-...