that's correct, early on when granite was more expensive to source, it was only about 1 cm thick then layered with wood or a composite under to get the thickness to match the sides. Nowadays granite is pretty cheap and cost effective compared to the polymer options. I personally prefer granite, especially the uniqueness of some patterns and the its natural. Though not without the radiation controversies....Our granite slab is thick. I can stand on it with out issue. One reason I use the one company. We also pick the type that is denser. Ours has been installed for 3 years sealed once, it has never strained and I am not careful. It is over a inch . no backing needed.
The slab in Florida house we sold. Skinny stuff it would break if stood on.