It's loading fonts. So squarespace needs to host those fonts, fine. But more to the point, it could be argued even the Squarespace CDN is "different" from the actual website, so we need CDN shims that forward local domain requests to the CDNs and return the results. All to hide an IP number for downloading fonts." Moreover, "host it yourself" is easy if you're technically skilled, but very, very difficult if you aren't.