When the same corporations own the infrastructure they are service providers of, competitors are in for a bad time. And when competitors have a bad time, consumers get a bad time. There’s no reason MS or Google can’t become Comcast.
The trade telecoms got is legal protection, guaranteed profit, monopoly-style protection in trade for digging all the communication lines that are needed to connect up the country (including "last mile"). Needless to say, they too the legal protection, monopolist position and profit ... and neglected or outright refused to dig the communication lines.
But this way, they can make 0.01% more money ... that's literally it. That's what the peering wars are about. Forcing others to pay. It's been going on so long there's literally a name for it in the theory of the internet protocols: "hot potato routing". Giving up extremely essential control for a tiny amount of money.
And, frankly, having been part of a few battles in the peering wars, some of it is just ego of higher ups.