I ran into a number of finicky issues building siftrss[1] a few years back. One I toiled over quite a bit was the discovery that Feedly, a very popular feed reader, does not support gzip. I haven't checked in recent years, but they may still not.
It's frustrating when you're forced to change the behavior of your "agnostic" application for the sake of a large, commonly-used third party tool in the ecosystem.