I think you got caught up by the misnaming of 'dark matter'. It's better to think of it as 'transparent matter'. It's non-interacting, not like a Dyson sphere w

I think you got caught up by the misnaming of 'dark matter'. It's better to think of it as 'transparent matter'. It's non-interacting, not like a Dyson sphere which would obviously be interacting e.g. from it blocking what's behind it even if it itself makes no emissions.