>Why does it matter who sends who how many bits?
Because that's what peering is.
No one gets to connect to a network, any network, for free. But if you have your own network, the company that owns another network might decide to hook up to yours for free, and you to his for free.
Supposing, of course, that your networks are roughly equal. Why bill each other, if your bill to him will be about as much as his bill to you? Doing all that accounting costs money, so it's easier to just connect to each other for free.
But this only works if both your networks are roughly equal.
If some jackass walks up to you and says "I'm selling crap to your customers, let me hook up to your network for free!" you aren't going to agree to that. It'd be dumb.
I really, really have trouble making sense of why so many people are ignorant of peering. It's going to be a really big problem too, because ignorant people are screaming for politicians to fix it, and neither the people nor the politicians have any clue at all.
> If Comcast is asking Level3 for massive amounts of traffic
Comcast is a network. It doesn't ask for traffic.
It lets people who are connected to their network communicate with each other. If only one party connects to their network, it is impossible in a practical sense to facilitate communication between the two.
Comcast doesn't guarantee connectivity to any specific host. It is a best effort service.
> Comcast just needs to admit their equipment simply isn't up to the task of servicing their own customers,
A kernel of truth in a turd of mistruths.
Yes, I suspect this too. But it's not their equipment... that stuff gets switched out every few years. It's their network itself. HFC isn't sufficient for a modern network.
Also, there's no point in them admitting this. That helps them not at all. And, since they're familiar with all the numbers, I also suspect that they know they can't afford to build a modern network.