I believe the author is discussing excessive buffering in the local hardware and OS, not the ISP's. He specifically calls out Intel and some Linux drivers as kn

I believe the author is discussing excessive buffering in the local hardware and OS, not the ISP's. He specifically calls out Intel and some Linux drivers as known causes. Additionally, he demonstrates that changing OS buffering parameters corrects the problem in many cases (going from 1-2s latency to 30ms).