With the crucial difference that the equivalent of 7/8ths of a a seat is still useful when it comes to bandwidth, especially for home internet.

Yes? But with orders of magnitude more difference. Let’s do a back of the napkin calculation:

Say your ISP gives you 100mbit/s = 1.08TB/day ≈ 30TB/mo. On gigabit that’d be 300TB. While you do have some heavy torrenters they are outliers.

Now I assume everything but TV/movie streaming is a rounding error for average Joe. Netflix says 1-7GB/h depending on quality. Average user watches ~3.2h/day (wtf is wrong with people!) but that’s ~100-700 GB/mo. Now that’s between 0.033%-2.3% of downstream bandwidth.

Of course, people generally watch TV at the same time of day, so it gets more complicated to provision resources. But there’s also no question that pooling bandwidth (over-provisioning) makes sense to reduce costs. The question is more about how much congestion is acceptable, and I wouldn’t trust shitty monopolistic companies to behave. But if you can handle eg Super Bowl or a World Cup final without degradation you’re probably good the rest of the year?