Joe,
The reason is the unpredictability of RSSI based on reflections, absorption. I'm not an RF engineer and my math skills are at best a first year university student level so triangulation is out, heat maps are out... not really but I don't want to over complicate things.
The simplest, most reliable and cost effective way I came up with was battery powered sensors that would already be placed in rooms (perhaps multiple), hallways, etc. that would be performing other functions such as the Moteino. Then use a range restricted keyfob also using a low cost RF solution as a beacon that deep sleeps.
This would have allowed me to keep the same protocols across multiple sensors and the only thing that needs to be reported to central 'business logic' would be, "user A is in range of sensor 1' and the logic only has to figure out that means, "user is in the Kitchen".
I don't need to know exact x,y,z coordinates. With enough cheap sensors that can only receive the beacon within x feet I can figure that out to determine an area/zone the person is in.
At least that was my thoughts. Still playing with ideas.