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.
"Thank you Joan for keeping up the comments. This snap dragon is called "chantilly mix" & I loved it last year so am growing it again but the seeds have been slow to sprout so might not be many. The larkspur mix was a hit as well! They…"
"Hi Joan, thanks for your comment. I haven't started planting this bed yet but I've noticed it looks like the vinca is coming back this year. Will probably see how well it fills in, then go get some more. We've had a…"