Maybe this specific feature should be marked as unstable and default to disabled on most kernel builds unless you add something like btrfs.experimental=1 to the kernel line or something
Parity support in multi-disk arrays is older than I am, it's a fairly standard feature. btrfs doesn't support this without data loss risks after 17 years of development.
If you're not interested in a multi-disk storage system that doesn't have (stable, non-experimental) parity modes, that's a valid personal preference but not at all a justification for the position that the rest of the features cannot be stable and that the project as a whole cannot be taken seriously by anyone.