Is it still the case that you can't start/stop hosted services from Server Manager? From my experience, it seems to be. I disagree with the assertion that hosted services "shouldn't need to be started or stopped like referenced services might." We are migrating from an old portal to a new one on a different server. We need to make sure that all scripts and url references in other GIS-related products have been pointed to the new services and nothing is still pointing to the old.
We've done all we can to make sure we have, but AFAIK, the only definite way to be sure we didn't miss anything is to shut down the old hosted services and see if anything is still pointing to them. We don't want to shut down the old portal completely as we aren't finished migrating other services. If anyone has a better workflow, I'm all ears, but regardless of the type of service, we should be able to shut it down if we need to.