APFS can't provide the stability that ZFS does because it hasn't been beaten on for long enough yet. I have a hard time trusting a new filesystem to store anything remotely important until its been beaten on long enough to find many of the nasty pathologies. Features don't matter as much as stability. Keeping your data safe is the #1 thing a filesystem needs to do.
Also, based on how the quality of the OS has been in the last few versions, I'm not sure I entirely want to trust brand new software from apple right now. In my opinion, they don't take bugs seriously enough, and a filesystem is a hell of a lot more complicated and important than a music player, web browser, or email client.
Because ZFS is deployed on consumer hardware of hundreds of millions of people?
No, zfs is instead used on ecc equipped servers in carefully managed environments.
The engineers who work on filesystems are not the engineers who work on music, mail, etc. Apple has been doing a lot of stuff under the covers with their filesystems, and it's all been rock solid so far, so I don't see any reason to start doubting them now.
Also, based on how the quality of the OS has been in the last few versions, I'm not sure I entirely want to trust brand new software from apple right now. In my opinion, they don't take bugs seriously enough, and a filesystem is a hell of a lot more complicated and important than a music player, web browser, or email client.