One guess I can make for the "hate" BTRFS gets is probably because everyone loves their data and doesn't expect to "fight" with a file system to get access to it.
E.g. Sailfish OS is perhaps the only mobile OS I know that uses / used BTRFS in production (and they adopted it nearly 6-7 years ago!). And some of its users have had issues with BTRFS in the earlier versions - https://together.jolla.com/questions/scope:all/sort:activity... ... in fact, I too remember that once or twice, we had to manually run the btrfs balancer before doing an OS update. For Sailfish OS on Tablet Jolla even experimented with LVM and ext4, and perhaps even considered dropping BTRFS. (I don't know what it uses for newer versions of Sailfish OS now - I think it allows the user to choose between BTRFS or LVM / EXT4).
Most users consider a file system (be it ZFS or BTRFS) to be a really low-level system software with which they only wish to interact transparently (even I got anxious when I had to run btrfs balancer on Sailfish OS the first time worrying what would happen if there was not enough free space to do the operation and hoping I wouldn't lose my data). Even on older systems, everybody frustrated over the need to run a defragmenter.
Perhaps because of improper expectations or configurations, some of the early adopters of BTRFS got burnt with it after possibly even losing their precious data. It's hard to forget that kind of experience and thus perhaps the "continuing hate" you see for BTRFS - a PR issue that BTRFS' proponents needs to fix.
(It's interesting to see the progress BTRFS has made. Thanks to your post, I may consider it for future Linux installations over EXT4. Except for the hands-on tinkering it required once or twice, I remember it as being rock-solid on my Sailfish mobile.)
And I get why (snapshots are wonderful), but opensuse, albeit tumbleweed, is also the only OS I've had lose its root filesystem and force me to reinstall. Some of us distrust btrfs for a reason.
(Details: Corrupted filesystem, happened twice, ~2019 IIRC, on a single disk system so not even touching the RAID code, first time couldn't repair, second some didn't try. Hasn't happened again and wasn't just a checksum error so I doubt that hardware is at fault but could be wrong.)
E.g. Sailfish OS is perhaps the only mobile OS I know that uses / used BTRFS in production (and they adopted it nearly 6-7 years ago!). And some of its users have had issues with BTRFS in the earlier versions - https://together.jolla.com/questions/scope:all/sort:activity... ... in fact, I too remember that once or twice, we had to manually run the btrfs balancer before doing an OS update. For Sailfish OS on Tablet Jolla even experimented with LVM and ext4, and perhaps even considered dropping BTRFS. (I don't know what it uses for newer versions of Sailfish OS now - I think it allows the user to choose between BTRFS or LVM / EXT4).
Most users consider a file system (be it ZFS or BTRFS) to be a really low-level system software with which they only wish to interact transparently (even I got anxious when I had to run btrfs balancer on Sailfish OS the first time worrying what would happen if there was not enough free space to do the operation and hoping I wouldn't lose my data). Even on older systems, everybody frustrated over the need to run a defragmenter.
Perhaps because of improper expectations or configurations, some of the early adopters of BTRFS got burnt with it after possibly even losing their precious data. It's hard to forget that kind of experience and thus perhaps the "continuing hate" you see for BTRFS - a PR issue that BTRFS' proponents needs to fix.
(It's interesting to see the progress BTRFS has made. Thanks to your post, I may consider it for future Linux installations over EXT4. Except for the hands-on tinkering it required once or twice, I remember it as being rock-solid on my Sailfish mobile.)