Google acknowledges this themselves, and it's mostly for compatibility reasons. Serving TTF to old browsers and WOFF for newer ones for example. Easy to verify

Google acknowledges this themselves, and it's mostly for compatibility reasons. Serving TTF to old browsers and WOFF for newer ones for example. Easy to verify yourself, make a request to the stylesheet from internet explorer and compare with the response you get if you make a request from a chromium-like browser, it'll serve you different contents.