In theory this is the right way to do it; however, the entire problem is that new users often cannot be as active as they would like precisely due to their limited resource credits. The only way to see how active they can be is by lending them the RC.
The benefit here is that undelegating RC is quite rapid (they're restored within 24 hours, if I recall correctly). So if a new user ends up being inactive for some time, we can undelegate and get everything back within a day.