BECAUSE they are funny. Queen were sort of funny, but I think they still sort of took themselves seriously. I do not find AC/DC funny.
The only time I have ever been reminded by the Darkness of either of those 2 bands is in the opening riff of Black Shuck. Please tell me a band that has never in its lifetime made a riff that ever sounded like another band.
I don't care if they don't have poncy artistic integrity, they are meant to be a piss take on the glorified rock bands of yesteryear and they are more fun to listen to than any other other band I have heard in a long time.