Because APFS is slllloooowowwwwwww on HDDs. On a 6xHDD promise thunderbolt array, it’s brutally crippling over time.

One reason is APFS is designed for SSDs and assumes each disk block has an equal latency to read it.

You can access an encrypted HFS+ partition from macOS and Linux machines natively. Very useful for sharing data between Asahi and macOS, and in general between Linux machines and macOS.