Google also "invented" it as part of SPDY (it's surprisingly difficult to find a clear reference, but I'm reasonably sure it was in pre-standardization-process SPDY too). For this kind of thing, one one hand it doesn't make much sense to apply a global opinion about a relatively minor thing to a company of that size, where different teams and their goals aren't aligned or even at odds. On the other, I wouldn't take GAE not having a feature as a big signal: its best days clearly are over and it's lacking/buggy/... in all kinds of places sadly.