Folks have modified their smokers with a variety of heating elements. A second OEM element, a 700 watt finned element, and a 900 watt finned element.
When you’re using 1,000 watts of heater element, you’re pushing the limits of the stock electrical system. Many dual element smokers use a PID to handle the additional electrical load. (A few folks report running two OEM elements on the stock wiring without problems.). I suspect that some of the PID crowd used their heater mods to justify equipment that gives the tight temp control available with a PID.