Why? Are you in a position where you can’t modify grub or fstab?
It's not a backup. It doesn't protect against mistakes, bugs, or the server failing in some other way. What it's good for is for ensuring that work keeps happening if a disk fails. And disk failures happen to be fairly frequent, since spinning rust is a rather delicate technology.
If somebody has to connect to the machine and fiddle with it by hand it means that the system has been down, possibly for hours, when that was the exact thing you were trying to prevent by setting up RAID on it.
> What it's good for is for ensuring that work keeps happening if a disk fails.
Different services have different priorities. I want my work servers to keep running, but my home server under the desk to stop until I replace the failed drive. Btrfs gives you a choice.