I have been in the telecom industry for for many years. The issue that most people don't understand is that the infrastructure is "shared" amongst all subscribers and somebody has to pay for it.
One of the common questions I always got from Telco operators is "how many subscribers can your mobile system handle"? My snide answer is "100 billion"....as long as nobody makes any calls. The question they should be asking is "how many simultaneous calls can your system handle?". Then the answer becomes 100,000 peak busy hour calls. The Telco customer should know what their *expected calls per hour per subscriber* are and then they can calculate the number subscribers they can handle.
The "expected calls per hour per subscriber" (or expected bandwidth per subscriber in this case) changes the calculation significantly. Netflix and other content providers have been a game changer in recent years because they have drastically changed that number. The ISPs know they can't provide every subscriber peak bandwidth at the same time. When subscribers used their "promised bandwidth" in 2 second bursts to quickly load a WWW page, the ISPs had no problem providing it. But now that subscribers are demanding their "promised bandwidth" in 2 hour "bursts", the playing field changes dramatically. ISPs, of course, can engineer for that load, but then "somebody" needs to pay for it. That "somebody" is either the subscriber in the form of higher ISP subscription rates, or the content providers in the form of "throttling fees" which they will undoubtedly pass on to their customers or advertisers.
Net neutrality simply shifts who is paying for the cost of all that equipment for our access. One way the end user will end up paying for it directly, and the other way the end user pays for it indirectly through higher content fees, or goods and services that are more expensive due to higher advertising fees. In the end we all have to pay for it.
I tend to fall on the side of Net Neutrality (and consequently would be willing to pay the ISP more for access), because otherwise the big players (Netflix, Google, etc.) will become more entrenched as they are able to pay the throttling fees while some upstart with a great service can't afford it.