I'm glad they don't, and would rather that everyone else just stop. It is an affront to my sense of control over my browser. Middle click is just as easy as left click; let me decide how I want to arrange my input.

How could the site possibly know what exactly I am trying to do with the content? Maybe I want to move forward from their site to another, never to return. Maybe I am rapidly opening a handful of probably-useless links in parallel, with the intention of closing all other tabs as soon as I determine that one of them has what I am looking for. Maybe I am opening a second window for some back and forth copy-pasta. Don't infringe on my controls, dammit!