alt Hacker NewsReferrer-Policy shows it can work. When the header is missing, browsers fall back to strict-origin-when-cross-origin. 86.6% of the sites we scanned don't send it, and we didn't count that as a failure for that reason. The other headers don't have a safe default like that yet.
That sounds more like it is a condemnation of all these other headers that can't work for 86.6% of sites by requiring nothing.