File systems are hard. They're incredibly difficult and incredibly important. It look a long time to get to ext4 and NTFS, and there's a reason HFS+ has stuck around for as long as it has, despite all of its shortcomings and limitations.

Even in the Linux work, thinks like btrfs, even though some distros consider it sable, is still treated with scrutiny. Back in the early 2000s, many Linux distros refused to install on XFS or JFS.

Apple's APFS rollout really does fell like it happened way too fast.