Not only that, it doesn't break anything at all. Referer is a completely optional header, and all this does is introduce a <meta> tag for controlling that. I hope more browsers pick this up soon!
And also let me enforce my own setting.
Chrome has supported this since about 2011. It is not actually new. And because it was implemented before the WebKit/blink fork even Safari supports it as well. Firefox is the 3rd browser.