So to detect bittorrent, they'd build a profile about how many bit torrent clients operate, the packet and connection creation patterns used, and then slap a throttle on. Looking at some independent analysis, these products might only detect 50% of the bittorent traffic, and have a false positive rate, especially for bittorent users also doing something else. And the ISPs don't care, they get what they need if they clamp 50% of the traffic.
So I'm not disputing that everything encrypted is a good thing, just pointing out that because it's encrypted doesn't necessarily mean the shaping equipment can't figure out enough to throttle bit torrent.
> If I had to guess, I'd say that they incorrectly thought that some specific IP address (range) serves predominantly one type of data. So they throttle by the only data point they have, destination ip, and the collateral damage is everything else hosted on that ip address.
This is plausible. As I recall, the way some of the equipment worked was it would sniff out DNS requests, and then mark the IP address as this destination. So if someone set's a rule for example.com, it might accidentally apply to alice.com using the same IP address.
My knowledge on the industry is out of date though.