If there is a physical limitation to the amount of light that can be produced by a light bulb that uses black body emission to generate light, then a standard of efficiency that exceeds that physical limitation is an effective ban on generating light via black body emission.
That's the way Congress loves to roll: they won't explicitly ban something they don't like (so they can save face with their constituents), but they'll do everything they can to make it untenable.
That's the way Congress loves to roll: they won't explicitly ban something they don't like (so they can save face with their constituents), but they'll do everything they can to make it untenable.