Just a few questions, this is the rule governing mast tip weight?

1.4.5 The weight that is measured at the mainsail hoist height of a mast lying perfectly horizontal with its base supported at the bottom edge of the mast section is referred to as the "mast tip weight". The minimum mast tip weight of a fully fitted mast, excluding standing rigging, is set at 6.00 kg for reasons of seaworthiness and to guarantee fair racing.

So what it is saying in other words is that where and how the mast is weighed will actually give the approximate half weight of the actual rigged mast?
If that is correct??? Then a fitted mast, less its standing rigging, has to have an approximate minimum weight of 12kgs (for the whole of the mast with fittings)?
(Does that also allow for the spinnaker halyard to be included in that weight if it is an internal halyard?)
If the above were correct, then by my calculations, even a fairly standard carbon fibre mast with fittings, would fit that minimum without having to add extra weight. I would have thought that any standard aluminium mast would be much heavier than 12Kgs any way
I suppose what I am asking is, assuming that my assumptions are correct (and I stand corrected if they are not) what is the point of having a mast tip weight as it would not effect anyone’s personal choice as to whether or not they wanted their mast in carbon or aluminium (other than a cost differential).