OK, but we're talking about hosting only a part of the website content on the CDN here. In this case - fonts. We can - and should - use the default font to rend

OK, but we're talking about hosting only a part of the website content on the CDN here. In this case - fonts. We can - and should - use the default font to render the text until the webfont has been completely loaded, using one of the available techniques. Unfortunately, even some high profile websites ignore this issue and block displaying the text until the font is loaded.