I'd rephrase that into skimmers are often driven away by a block of text while readers are driven away by page-filling images. There is an optimum between these two which attracts people from both sides of the divide - a few targeted images can enhance a text and make it look less imposing to skimmers.

And in all fairness, this isn't just a web thing. Most newspapers have historically used all manner of graphical techniques in addition to images to break up text blocks such as subheads, callouts, graphics, lines, etc. (Although, also to be fair, historically newspapers also tended to try to include images that were directly relevant to the story rather than picking random stock imagery.)