This is a fair point. I think that the instability of early releases of BTRFS and the (lack of) commitment of especially RedHat made me not spend too much time working with it. The lack of a RAID solution made it not feasible for my purposes for a long time, and I was already quite familiar with ZFS through working with Solaris and FreeBSD. Trust in filesystems is hard won and easily lost[0].

I also think the popularity of FreeNAS especially contributed to the popularity of ZFS.

[0] I still look at XFS skeptically after a crash I suffered nearly 20 years ago. It’s not a rational fear, but it’s still there.