It’s not prioritization of the code - it’s relatively little implementation and low maintenance but security is critical here and everyone is very afraid of compressors because gzip, jpeg and various others were pretty bad. Zstd, unlike lz4 before it (at least early on) has a good amount of tests and fuzzing. The implementation could probably be safer (with fairly substantial effort) but having test and fuzzing coverage is a huge step forward over prior industry norms

I qualified it with compelling which means only including formats/encodings which have demonstrably superior performance in some non-trivial respect.

And I qualified it with mature implementation because I agree that if there is no implementation which has a clear specification, is well written, actively maintained, and free of jank, then it ought not qualify.

Relative to the current status quo, I would only imagine the number of data compression, image compression, and media compression options to increase by a handful. Single digits. But the sooner we add them, the sooner they can become sufficiently widely deployed as to be useful.