Maybe for you Dick, but not everybody can afford to test every model type...
If I tell you that a model has a wingloading of 28oz/sq ft, it won't tell you much until you know the actual size.
But if I tell you that model's cubic loading is 7, then you'll get a better idea whether it is capable to slow landings without needing to know the model's actual size.

For instance, if the Thunder Tiger trainer had 28.5 oz/sq ft wingloading it would fly like a brick, while your 1780 sq.in CAP flies like a feather despite same wingloading.
However, the Thunder Tiger has only 17 oz/sq ft wingloading, which is the same cubic wingloading 8 as your 1780 sq.in CAP.
I've flown several models since I begun for a decade ago, some were kits, other scratch build, some survived other didn't, but what does it matter, the question is often how heavy it is related to wing area and model's size.
Using cubic wing loading you don't need to bother about the actual size of the model.