"HTTP servers will often support compressing the response, but almost never do they allow compressing the request body"
What doesn't have great support for Content-Encoding headers?
What doesn't have great support for Content-Encoding headers?
See this stackoverflow question for one brief discussion: https://stackoverflow.com/q/20507007
I've looked around for this feature and rarely found it to be supported... but it's also rarely discussed.
If built in support that works with one config statement isn’t “great” support, what is?
Apache being the only thing to support it also wouldn’t count as great. They specifically mentioned uncertainty around nginx. Have you tested any of your APIs to see if they support it?
As for if I've "tested it". No. Because as I said: this is going to benefit only a small niche of application types. The vast majority of applications built by the vast majority of developers are going to unlikely to see any benefit at all from this type of compression, because it's not a common pattern.
Add to that, most applications are likely running in an environment where spending precious CPU cycles to compress data to send over a pipe that they're unlikely to saturate anyway, is not a winning proposition.