But why, though?

I am fond of reading all those January articles about cleaning and organization, but I just encountered a bewildering article on Well + Good on how and when we should be disinfecting old/used books. I have so many questions! Did they really need to tell us that an eraser will remove old pencil marks? And a dusting cloth will remove dust? Meanwhile, their other tips are bizarrely hardcore. Like, if I find a book that is infested with bugs, that sucker is getting thrown out. I don't care if it's a family heirloom; it's gone.