Pretty cool looking service. Since I've never heard of it, I wish the down voters would explain the problem with it (at the time of writing it's a dark gray, so only a little negative).
Is it simply that people don't seem library CDNs as a source of privacy piercing data?
SRI (no changing content for a specific user) + crossorigin ('The "anonymous" keyword means that there will be no exchange of user credentials via cookies, client-side SSL certificates or HTTP authentication'), no referrers via meta tag or header.
The other end gets your IP and browser UA, with nothing else. It is pretty low on the totem pole of worry.
That certainly wasn't spam, but unfortunately I was in the middle of something else at the time and didn't have time to post the explanation I probably should have included.
Is it simply that people don't seem library CDNs as a source of privacy piercing data?