bcachefs was already working at its own pace prior to being accepted in the kernel. It could have continued doing so for years until it was really "ready".
Instead it got kicked out because Kent constantly ignored the kernel's contribution rules and is unlikely it will ever be accepted back into the kernel.
That would be a shame since there is nothing else over there with the same set of features. Disregarding drama, I'm telling you it’s that good.
I'd really appreciate it if we could drop the FUD over contribution rules. There are no such rules, it is explicitly Linus's way or the highway, and I already replied to that elsewhere.
And it went in when it did because Redhat was pushing for it and claiming to be supportive - but that never materialized. They wanted to get something for free without investing, or putting in the absolute bare minimum.
A _lot_ of people were saying publicly and privately "dear god yes we need something better than btrfs" - but no one from the existing kernel community was interested in stepping up.
Community's still growing, though. A lot of people have gotten active in making sure bcachefs actually works well for people end to end, and there's a hell of a lot more to shipping a filesystem than just writing kernel code.