ISPs are not the internet. They don't own the internet. They don't control traffic on the internet. They only control traffic between you and the internet.
Here's a thought experiment. What would you think if an ISP decided to prioritize all traffic coming from Speedtest.net by Ookla - The Global Broadband Speed Test in order to make it look like their connect was faster than it actually was. Lets say the result of this was that is that your connection lags every-time someone else decides to run a speed test. So now you cant watch a glitch free movie because your ISP wants to pad it's speed scores.
THIS is what you're arguing for.