Members of the front-end community are among the most likely to champion HTTP/2. The spec may be finalized, but HTTP/2 is incomplete without a developer ecosystem to support it.
server push (no more inlining!) prioritization https required by browsers * through connection coalescing, hosts that resolve to the same IP can share the same connection
before the client knows is seriously challenging, especially for general-purpose web servers which need to allow site owners to tune certain aspects for best performance and reliability. The heuristics for determining what to push vary. https://caddyserver.com/blog/implementing-http2-isnt-trivial