Why would anyone go through all that hassle when you can get a ESP8266 from aliexpress for less than $2? The skilled labor cost alone needed to desolder the chips is going to wipe out any savings, not to mention the hassle of fabbing custom PCBs to work with your hodgepodge collection of microcontrollers.

There are countries where people would sit all day desoldering phones if they were paid $2 for each. Also even in my country minimum wage is less than $2/hr (although that is rare).