Yes, the science of TCP buffers is *unrelated* to other buffers below it. Simply because TCP is in charge of everything: reliability, end to end flow control, and network congestion avoidance, while the rest below is in charge of none of it.
Confusing these two very different buffering roles (TCP versus below TCP) is a huge mistake.
On the other hand, I wonder why a leaflet was needed at all. TCP auto-tuning is supposed to have fixed this problem already?