I don’t think there’s super meaningful data to be gleaned from server-side tracking, especially with browsers increasingly sending little to no information to third party resources. This is CSS, not a JS script that might collect more info and phone home. So yeah, the site going blank is higher priority to me than them knowing if I, the service provider, not my users, prefer Roboto over Open Sans, or if most users now support woff2 vs. ttf. But either way, we’re not going to use them anymore.
CSS can be crafted to conditionally load additional resources, which means it can be a vector for fairly sophisticated information gathering and tracking. For example: https://github.com/kkuchta/css-only-chat
