The return from a spread operation would be a new array or struct containing the items that were spread out. Would allow for much cleaner functional programming style where avoiding mutating data is key.
Merging objects is one use case:
Oh, and another, converting a string into array:
As a side effect, this could eliminate the need to do things like
and instead you'd be able to do
Not the only use case (see link above), but one that I run into frequently and wish I had a spread operator.
The spread operator makes different use cases very convenient to write, so a big from me.