Until now, while most people don't use ad-blockers and browsers have accepted third-party cookies, there's an advantage to loading a resource from another domai

Until now, while most people don't use ad-blockers and browsers have accepted third-party cookies, there's an advantage to loading a resource from another domain, since an ID created and stored by doubleclick.net on site A could be read by doubleclick.net on site B, allowing for cross-domain tracking. As third-party cookies increasingly get blocked, I think we'll see that more and more.