> Why would it need to be 220 V in the "socket" for the bulb? Why do we need lamps themselves to just be a frame to hold a wire, why not put the driver circuitry in there to step it down to whatever voltage we decide to drive the DC LED bulbs at?

I was talking about the lamp itself. Maybe I used the wrong term? I meant the fixture which holds the wire and expects a bulb. That fixture needs to go into mains, because that outlet may have to also service something else entirely.

Now, sure, usually those fixtures tend to be larger than the bulbs, so they could hold the conversion circuitry. I'd be fine with that. But the commenter I was replying to talked about having an alternative DC circuit for the lights.