A lot of muscadines have a thick skin and seeds- especially older varieties.
That was also true of Old World grapes until pretty recently! It took a lot of selective breeding to get thin-skinned seedless grapes.
We're getting there with muscadines too.
Ok let's talk about Old World grapes, Vitis vinifera.
They were domesticated in the Middle East, Caucasus Mountains, and/or west Asia.
That means unlike southeastern muscadine grapes, they like dry weather! They're a popular crop where water's more scarce.