I think the problem with btrfs is that it entered the spotlight way to early. With Wayland there was time to work on a lot of the kinks before everyone started seriously switching.
On btrfs a bunch of people switched blindly and then lost data. This caused many to have a bad impression of btrfs. These days it is significantly better but because there was so much fear there is less attention paid to it and it is less widely used.
Both Fedora and openSUSE default to Btrfs. That’s all the praise it needs really.
With Bcachefs still being relatively immature and the situation surrounding (Open)ZFS unchanged, Btrfs is the only CoW-viable option we got. So people will definitely find it, if they need it. Which is where the actual issue is; why would someone for which ext4 has worked splendidly so far, even consider switching? It’s the age-old discussion in which peeps simply like to stick to what already works.
Tbh, if only Debian would default to Btrfs, we wouldn’t be having this conversation.
what ZFS situation?
I’ll keep it brief. But it comes down to the fact that, out of the more popular distros, it’s only officially supported on Ubuntu.
https://openzfs.github.io/openzfs-docs/Getting Started/index.html
i’ve found to work without issue on Fedora, Arch and Ubuntu so maybe it’s supported very well