This is more or less what I've heard. Early espresso machine tech was based off mechanical relays, and they didn't play well with early electronic temp sensors.

This is more or less what I've heard. Early espresso machine tech was based off mechanical relays, and they didn't play well with early electronic temp sensors. Also, temperature stability was not really a thing anyone was talking about to that degree, so it wasn't a priority for manufacturers until noise was raised.