That's true though. If you're a tier 1 network then you can advertise whatever you want, and if they cut you off on that advertised address, then you can cut your peer's address off. And, if you're big enough, the peers can't just disconnect from you altogether or they themselves would lose connections to other peers. This is why BGP and the other routing protocols are so cool; you can get control of the internet if you just buy some routers and create a way to get advantageous peering relationships. It's an offer you can't refuse.