You missed the point, you compare to DCL with cash vs DCL using DVC points.
I'm not saying you should or should not no anything, they're your points, you can do what you want within the rules. However, from a dollar standpoint, buying points to use for cruising is a losing proposition. One might be better off selling the points than using them for DCL routinely. You could certainly rent and then use the cash for any cruise (DCL or otherwise) but I don't think that's a great option either long term though it's certainly better than routinely using them for DCL. It sounds like you haven't bought yet, if that's the case, do yourself a favor and buy just the points you'd use at DVC and pay cash for the cruise, you'll thank us later.