Agreed that APFS is not a good choice for HDDs, except in very limited circumstances. If you have any kind of active writing going on with an APFS file system on HDDs, that's where the performance really gets bad. Using it for "archival" or backup purposes (e.g. Time Machine) seems to work OK.
Yes ZFS is a nicely done file system. But I'm not one of those that thinks it's a panacea and I don't disagree with Apple for not dealing with Oracle (If you think Apple is bad, Oracle is 10x worse). ZFS gets its performance by use of caches - both in memory and by using high performance cache disks. MacOS users complain now about memory utilization, can you imagine if they found that there's no free memory??
And ZFS's ability to recovering from a block corrupted due to "bit rot") requires essential a mirror copy of the data.
So please bear with me if I think that ZFS works well for a server-based operating system like Solaris, but not so great for a desktop system.
I do believe that AppleRAID is still available in Disk Utility and through diskutil.