It’s a really convenient property if you’re maintaining long lists since you can easily re-order items in a list without having to re-number each item.
It seems like for those situations it would be much nicer to just have something like \item in LaTeX. It's still readable in plaintext, but wouldn't break things.
That's a perfectly reasonable use case that should be supported. But it should require explicit activation (a tag, etc). A formatting engine should not rewrite content unless told to explicitly.