And you'd need a motherboard with Intel's top of the line chipset (Z170) for TB support. Lots of people choose to skimp on the extra $30 or so as the perception at the moment is that it's only necessary for overclocking.

Most Z170 motherboards don't have a TB3 port either, as it's an added cost that most people frankly don't give a fig about. In PC motherboards, USB-C has almost total market penetration; TB3 almost zero.

TB3 is much more prevalent on PC laptops, but still nowhere near common.