The issue addressed by this spec (preloading latency) is only partially addressed by HTTP/2 push. As another user pointed out, the spec notes in its introducti

The issue addressed by this spec (preloading latency) is only partially addressed by HTTP/2 push. As another user pointed out, the spec notes in its introduction that push (a) requires the replying server to be authoritative, and (b) wastes bandwidth in the case that the content is already in the client's cache. In particular, the spec also notes it is reasonable to only implement in HTTP/2 due to a specific security consideration. [1] https://tools.ietf.org/html/draft-ietf-httpbis-early-hints-05#section-1 https://tools.ietf.org/html/draft-ietf-httpbis-early-hints-0...