That's great if your content can fit on one physical drive - but that's not the case for everyone. However, even that aside, I would likely still use ZFS even

That's great if your content can fit on one physical drive - but that's not the case for everyone. However, even that aside, I would likely still use ZFS even with your solution since I make sure of other ZFS features aside just running a software RAID (eg ZFS snapshots, checksumming, send/receive, etc).