主要是依據 Google Chrome 的流量數據，HTTP/2 大約佔了 25% 的流量 (目前檯面上大網站的 HTTPS 都支援了)，而 SPDY 只剩下 5% 的量：
Over 25% of resources in Chrome are currently served over HTTP/2, compared to less than 5% over SPDY.
另外一個是對 HTTP/2 NPN 的支援將同一個時間關閉，只支援 ALPN：
At the same time, Chrome will stop supporting the TLS protocol extension NPN, which allows servers to negotiate SPDY and HTTP/2 connections with clients. NPN has been superseded by the TLS extension ALPN, published by the IETF in 2014. ALPN is already used 99% of the time to negotiate HTTP/2 with Chrome, and the remaining servers can gain ALPN support by upgrading their SSL library.