We have loads of moss in our garden and grass (Oregon). I often wondered the same question. Usually when I'm removing it from my flower beds. I have yet to see any positive benefit to this kind of moss in flower beds.
"Thanks Charlotte. I just moved them to the shady spot next door. We played musical pots today as one fuschia had to be taken under a tree for comfort & every other basket moved over one notch less sunny. My really sunny corner now has no flowers…"