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.
Stop spreading disinformation (again). Wayland was a fucking mess and caused countless of issues, especially in a lot of “edge cases”. Meanwhile, dumbos were spreading lies about how it runs perfect and without issues while I kept switching back to X after merely minutes to hours whenever I tried to use Wayland again. It’s just bullshit that never was grounded in reality. Even now there’s games & applications who don’t run with Wayland, and likely never will since they have zero incentive to do so or aren’t even in active development anymore and that stupid X11 bridge still is required to run in the background for a lot of them.