[ajb]

That's a different issue though. I should have been more precise with my terminology. The way it usually works is that there is a scheduler at the bottleneck. Let's for simplicity assume that the customers at a particular bottleneck have all got the same advertised rate, but the bottleneck is less than the sum of these. Say there are 10 customers with 100Mbps each but the bottleneck is only 500Mpbs. Then if each of the 10 customers are maxing out their usage, they will each only get 50Mbps, which is less than the advertised rate on their service. What I meant was, playing games with congestion control won't reduce any other customer below that. (There are different options for how the scheduler could work if the customers have different limits; it could just cap them to their limit, or it could weight their share according to their limit).

I guess you are right that buffer bloat problems could pressure ISPs to avoid overprovisioning, and any solution to bufferbloat could take the pressure off. But you can also get bufferbloat and other latency issues without overprovisioning, so it doesn't seem to me to be a good reason to hold off implementing solutions to them.