it is quite silly to say EXT4 exists for (your) said reasons. Btrfs isn't even a 'production' file-system and is piss-pot slow. (and ask yourself; which is in wider use, and why is that? ~ and no, it's not just because btrfs is newer, it hasn't proved itself to be a viable replacement yet). I didn't get the impression that a user's comment was SSD exclusive (although he can correct me if i am wrong), because HDD tests would also show EXT4 wiping the floor with btrfs too. The fact is btrfs (while very promising) isn't ready for prime-time, so this is not really a case where EXT4 is there just as an option for those who need the performance.