To be clear, I'm not expecting btrfs (or any filesystem) to avoid corrupt itself on unreliable hardware. I'm not expecting it to magically avoid unavoidable data loss.

All I want is an fsck that I can trust.

I love that btrfs will actually alert me to bad hardware. But then I expect to be able to replace the hardware and run fsck (or scrub, or whatever) and get back to the best-case healthy state with minimal fuss. And by "healthy" I don't mean ready for me to extract data from, I mean ready for me to mount and continue using.

In my case, I had zero corrupted metadata, and a second copy of all data. fsck/scrub should have been able to fix everything with zero interaction.

If files/metadata are corrupted, fsck/scrub should provide tooling for how to deal with them. Delete them? Restore them anyway? Manual intervention? IMO, failure is not a valid option.