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!
By the way, to enforce sane behaviour on decidedly not sane websites: Death to _blank addon for Chrome[0]. There was one for firefox too, but can't find any working with current versions..
0: https://chrome.google.com/webstore/detail/death-to-blank/gne...