It's 2016. If you are still deploying RAID, you're doing it wrong. Seriously guys, ZFS. Look it up.
* outboard RAID provides write amplification across physical devices
* soft RAID1 (simple mirror) is nice for things like boot volumes and easy to fix when it breaks
But yeah, ZFS and similar strategies work much better than soft RAID-5/6 for file store resiliency across visible LUNs.
I think you perhaps meant fan out, which is partially valid but addressed in the submitted article - i.e. bus speeds have improved greatly. In fact to the point where you can easily have no bus at all: point to point PCIe lanes to each NVMe device.
A zmirror is simple too, and gives you boot environments so you can roll back failed upgrades and other magic.
Reason for that is that adding a disk to vdev will require rebalancing everything and considering complexity of zfs, you better just make a new raidz with 4 disks and move data over, otherwise it might just take ages and complicate things a lot. This is obviously not ideal for a home user, but zfs was not created with a home users in mind.
Btrfs supposedly should let you do this, but their raid5/6 is still unstable - probably for a reason. In fact, this is not such a big deal. You can add disks to a zfs mirror (and it is real n-way mirror, not btrfs raid1 thing with multiple disks), you can add mirror vdevs to raid10 setup. If you are making raidz1/2/3 just make sure you understand that you can't expand it by adding more disks.
And yes, most people should default to ZFS for everything on FreeBSD/IllumOS/Solaris/Linux. There are specific cases where you should use XFS or UFS on these operating systems such as fail in place and overlay filesystems (HDFS, Ceph, Swift etc) but times have changed, the tables have turned, these non-ZFS filesystems are now expert territory with here be dragons warning label.