Water pump GPM?

Been researching more today... It seems all the systems I see have controllers of one type or another, some keep the thermostat, some dril a hole in it and some do w/o a thermostat altogether(assuming I read the lit right).

Would someone clue me in. Why couldn't the remote elec pump with a recirculating loop for lubrication/cooling of the elec motor, simply replace the mech pump? If the remote pump is running all the time, the thermostat would control engine temp anyway? Your mech pump is running all the time.

What am I missing?

Thanks again