I’m running a 60TB btrfs RAID with all the bells and whistles myself and just recently had an instance of some file being fucked up (probably just the wrong metadata bit being affected or something), which I noticed because btrfs send would repeatedly crash at that inum. All the redundancy may be there, but sometimes it’s not able to recover automagically.

Not hating on btrfs at all - it helped me recover from a few fubar situations that could easily have been total data loss - but magical thinking (about all the fancy features) is dangerous.