Excellent point. A transformer doesn’t propagate DC very well or at all.
I forgot about....
So some wall warts for example that you use to charge your phone probably use a transformer. Cheaper that way plus you get safety isolation for free. Sill it has to regulate to DC for the gadget. But it is moot because you still have a transformer in the path.
Larger devices like a PC will have a switcher since they consume more power and are more efficient. Hey maybe a house level DC voltage that distributes standard DC voltages and a high level that eliminates the need for an inverter.
Anyway, lol.
Very few of today’s walwarts use xformers.
China makes switching ones almost free.