Comment by Aurornis

DAC cables use twinax. Properly terminating twinax is not easy. It's not as forgiving as twisted pair going into an RJ45.

DAC cables have a limited length range. It's not like 10GBASE-T where you can run the cable hundreds of feet and then put a connector on exactly where you need it. The cables only work at short distances so it's easy to stock the cable sizes close enough to everyone's needs.