I am sorry you have failed to understand it properly.
I think your uh, claims were pretty easy to understand at first, they were just wrong. The "senior bod at BT" stuff did seem to disappear off on a tangent though.
The self regulation part of tcp expects packetloss to dissapear when it "slows down" which it typically will do in a normal situation, of course that doesnt happen when an intermediate router is the cause.
Once again, and I can't tell if you do this on purpose or just don't understand why it matters, you've confused two separate cases. If the intermediate router is faulty and is dropping packets or inducing unrecoverable errors as a result of a fault without any congestion, slowing down won't help. Somebody has to repair/ replace the faulty equipment.
But where an intermediate router drops packets due to congestion on a link, slowing down will help, in fact it's more or less mandatory as we saw before. Everybody will have to slow down, and this allows everybody to continue to make efficient use of the link (albeit with their throughput constrained).
Check out the graphs Level 3 released when publicising deliberate congestion on major ISPs in the US (L3 said that they don't see this problem in the UK due to effective competition between ISPs). At peak times these links saw hundreds of thousands of packets dropped every five minutes, which seems like a lot, but this is 100Gbps, so a few hundred thousand packets in five minutes is a tiny fraction of all packets. That's possible because each dropped packet isn't just one less packet to be sent over that link, it's also functioning as a signal to somebody's TCP/IP stack to take its foot off the accelerator.
The other thing you'll see, or rather won't see in those L3 graphs is the real error rate. It's zero throughout the week-long period of the graphs. That's pretty typical. If your packet didn't arrive it wasn't because of an error, it was because of congestion.