Verizon's advantage should be obvious: they also sell TV service which is in direct competition to Netflix. If Netflix works poorly, that's more customers potentially signing up for FiOS TV.
I feel like this is what people often forget in the net neutrality debate. The pipe providers have a horse in the race (FiOS TV On Demand, XFinity On Demand) and we need to make sure they aren't rigging the race so to speak.
Going beyond that, they typically have a monopoly or duopoly as an ISP, while they're subject to competition as a TV provider.
Much of net neutrality can be reduced to "don't let monopoly ISPs leverage that into a monopoly in other services".
If Verizon didn't offer TV, this wouldn't really be a problem. If there were 17 other broadband ISPs to choose from, this wouldn't really be a problem. But Verizon does offer TV and they're one of two choices for me and most of their other customers, so it's a problem.
It's even stated parenthetically in the blog posting when comparing European and US Level 3 and Verizon peering utilization, the former ~18%, and the latter ~100% "(where Verizon sells broadband to its customers and sees Level 3 and online video providers such as Netflix as competitors to its own CDN and pay TV businesses)"
Furthermore, if Verizon degrades connections to whichever ISPs Netflix uses, then they have leverage to get Netflix to pay Verizon to peer. If they make it so that the only way that Netflix can offer their service is to pay them for it directly, then that is more money for Verizon. Very clear motivation.
