Bill; Let me guess where you are headed:
Suppose the Earth was once (completely) covered with a layer of continental crust 13 kms thick.
Since continental crust now only covers about a third of the Earths surface, where is the unaccounted for
2/3 * 510,000,000 * 13 = 4,420,000,000 km³ of continental crust.
Are you interested in the volume of continental crust so you can account for the "missing" two thirds by stacking it up in 39 km high blocks (interestingly, Alfred Wegener suggests exactly this).
But, if you say that it is now incorporated in 39 km high blocks of continental crust, then who picked up the 13 km thick blocks and stacked them 39 km high,.... maybe, God?
What incredible force lifted and stacked these blocks.
Or, what even more incredible force might have compressed 13 km thick blocks into 39 km thick blocks?
Since no sufficient force is postulated (within plate tectonics) the idea of finding the missing continental crust in this way is flawed.
(Of course a planetary collision would have had the energy to do this, but in my theory the missing 2/3's is accounted for by the mushing of a large amount of continental crust in the mantle, the expansion of the oceans and the fact that one started with the continental crust completely covering a smaller planet.)
By the way, plate tectonics never claims to have done such (compressing or stacking of continental crust).
It is claimed that plate tectonics has raised mountains, however, these mountains are but a small surface feature on such blocks and comprise a very small percentage of the mass of the block.
How these huge blocks of continental crust came about, has never been explained (by traditional theory).
What caused them to be about 40 km high, has never been explained.
What caused the sides of these blocks to be nearly vertical, has never been explained.
Why these blocks only cover 1/3 of the Earth's surface, has never been explained.
In fact, only the PreEarth-Heaven collision explains these last four things.
As to whether you need a crust or not. Assuming the word crust, is here describing something like the shell of an egg, then the planet does not require a crust. However, as Bill has said, both the continental and the oceanic areas have a crust.
The two crusts are quite different in composition (and thus properties).
The oceanic crust averages about 8 kms in thickness, whereas, continental crust averages about 40 kms in thickness.
