Why Use Aluminum for a TT Platter?

Just look at the platter of the relatively inexpensive ($2k) Nottingham Spacedeck. It's a minimalist design table, and I bet that the platter alone costs at least half, probably more. I have no idea what it is made of but the thing is quite heavy. As I understand, that's what mostly makes Nottinghams sound the way they do - the platter.
Cooper with lead and steel in a sandwich style sounds good to me. And a beer please.

Viridian thanks for the trademark education but Michell platters are Carbon infused acrylic that DO contain Vynil.
Cheers

"Belt drives...in terms of speed accuracy, are clearly inferior to properly implemented direct drive tables."

Humm, proof, evidence to back this up?

Nothing cogs like a DD. The mass of the platter has nothing to do with flywheel inertia.

I just know in direct comparisons in the same system between VPI tables: Aries 3, Aries 1, Classic 1, and Classic 2 it appeared consistently whether with or without a mat that the new aluminum VPI platters ring like a bell compared to the VPI super platter and acrylic platters. Resonance, noise, and brightness were in abundance compared to the others.