> I am sure that the built-in Intel Ethernet ports on most motherboards have made Network Cards obsolete at least for the Home Market.

Someone is still making a NIC chip, they're just selling it to the motherboard OEM, instead of selling an add-in board to the customer (or selling a chip to the add-in maker). In a way, this is more sales, because desktops tend to come with a wired nic and a wireless nic, and so do good laptops.

You are understating how integrated this stuff is. If you make an Intel client motherboard, all you need to add for the network is the phy, jack and some passives.