What I'm seeing...
What I've been seeing is this tendency for some ISPs to have dropped peering agreements in favor of a smaller number of higher bandwidth links. Some traceroutes between ISPs here in eastern Iowa that used to route locally (so 5 or 10 mile round trip) and more recently would route through Des Moines (~200 mile round trip) now route through Chicago (~440 mile round trip).
I agree with Big Ed, in principal, the cable plans all have GB limits, and overage, the customer's paid for those GBs. and the ISP should deliver. The provider of whatever service buys enough bandwidth to provide their service.
So, the squabble you have now is some of these providers (TWC in this case) failing to maintain adequate bandwidth to these exchange points that Level 3 and Cogent (to name two) use. In Verizon's case of slowness with Level 3 (and so Netflix) (even after Netflix paid some fee to Verizon), Verizon's own diagram showed they have plenty of backhaul (I assume fiber) running from the exchange point to their backbone network, and plenty of backbone capacity, but a link at the Los Angeles exchange that runs at 100% utilization. They have an 8-port 10gbps switch with only 4 ports hooked up, they could double their capacity at this exchange point for the cost of a few patch cables and solve the problem, they just won't.
It's tricky, because TWC (and Verizon etc.) really aren't throttling anyone, so it's probably not subject to the open internet rules. But, I do think they are being a bad actor by collecting plenty of money from their paying customers to maintain adequate connectivity, then expecting others to pay for it. If the US internet market were in better shape, it wouldn't be a problem, if your ISP failed to maintain good enough connectivity you'd move to one that does, but there's many markets here with few choices.