Well, both matter - it's a supply/demand curve. The seller here seems to be assuming that the demand is relatively inelastic, and the opportunity cost of the seller's time (which is apparently finite) needs to be factored in.

So in essence what you have is a seller determining which type of the two accounts to make. He will not be able to re-use the HN accounts as much, and therefore he makes less per unit of time from them, and must charge more to make them worth his time.