Yes, there's a difference between hoarders and merit sources. The prior ones earn merits to gain sMerits while the later ones get a fixed or varying amount of merits per month. The merit sources could be hoarders if I'm not wrong because it's their decision to send merits to which worthy posts while the hoarders that you tried to mention can't be merit sources unless they properly make a merit source application thread and wait for Theymos's decision.

Now back to the main topic, the sMerits those hoarders earn aren't given to them easily because they try their best to make very high quality posts/threads, and sometimes despite making good quality posts/threads they won't get any merits. The sMerits they earn are 1/2 of the merits the earn from their posts/threads and that's why they contribute those sMerits to either someone whose posts/threads they like or they send it to whoever's posts/threads they prefer. It's their own decision to either hold those sMerits or send those to someone who deserves those sMerits, and no one can or should force them to send or not send the sMerits that they have.