Preamplifier power supply

There is another thread talking about a custom made tube preamp that sports an oversized power supply so much so that the unit weighs 75 lbs (34 kg). The owners of these particular devices have only accolades for the sound that this special preamp creates. Of course their descriptions oft include the size of the power supply as though any preamp worth of hifi should have a power supply capable of driving speakers. I have seen that there is some science to putting an oversized power supply into a preamp for improved noise performance and voltage stability. Beyond that, I do not see the point. Unless I am mistaken, the power output (audio power) of a preamp is, at most, about 50 milliwatts. That is assuming a 20k ohm impedance looking into the amplifier. I have seen some preamps boasting 250 VA power supplies. All that to deliver 50 milliwatts? Sure, there are the tube heater circuits to power and other ancillary circuits, but that is not the case with SS preamps. It this just a case where we as audiophiles expect our preamps to be big heavy boxes with gobs of reserve power and so the hifi builders deliver to those expectations? Preamps have had oversized power supplies for decades now. It just seems like a type of arms race that each generation of preamps must have even bigger power supplies to show some type of advancement in technology. I remember when very expensive SS preamps could be left on all of the time because they consumed little more power than a night light.