I don't think they were remiss , they did mention the presence of rock art, just not what is special about Orkney in relation to the subject .
That's for the anoraks .

In fact if they hadn't mentioned it all it wouldn't have mattered , as far as I'm concerned
Never noticed a mention of grooved ware , as yet , and that is far more important in relation to the premise of Orkney being central guff .