I'm not sure about @riverhead, but @roadscape delegates about 90% of his stake, which I think is a great thing to do.
I am trying to grow different red fish with my Minnow-ASAP initiative to strengthen the middle class on STEEM, so a delegation would come in handy. But most of the users I have contacted haven't replied or have declined the offer. It's a shame to see all that power go to waste.