Because often it's a crippled or broken experience, where half the images are missing, or you can't zoom, or the text is cut off, or the columns too narrow. Ed

Because often it's a crippled or broken experience, where half the images are missing, or you can't zoom, or the text is cut off, or the columns too narrow. Edit: Ironically, most of the issues above impact me the most when I really am on a mobile device.