You mean implementing or criticizing? A day late and a dollar short seems like the better idiom for most HTTP features implemented at this stage.
Everyone: HTTP2 is the bee's knees
GP: No it isn't that great.
time passes
Everyone: Oh yeah, HTTP2 isn't that great
GP: You see? I told you that first
Everyone: Well being early is the same as being wrong.
You see how that's not an argument here? GP was right. They were early and right. In financial markets the saying holds because if you invest too early you just lose money while the market's understanding catches up with you but here we're talking about implementing a standard (which comes with a cost). Everyone who jumped on the HTTP2 bandwagon incurred that cost. People who stuck with HTTP1.1 did not. Now everyone admitting they got it wrong have to back HTTP2 stuff out have to incur a second transition cost. The people who were early and right don't pay that either.