Ask HN: Using consumer cellphones for an IoT network?

I have been looking into LoRaWAN for a low cost waterproof asset tracker I am looking at building. AFAIK, the primary benefits of LoraWAN over say LTE-M or cellular are: no connectivity costs and potentially lower power consumption.

What I'm wondering is: why can't we use our own cellphones as the "base station" that the IOT device talks with? We can do this with bluetooth and WiFi, why not cell? Is it the LTE protocol that prevents it? Physics? What am I missing?