Right now blockchain.info maintains around 3,000 connections does this increase the amount of wasted bandwidth due to duplicate peer messages?
I noticed them taking up a bunch of slots on my own nodes (e.g. 6 total sockets, across multiple) and blocked them. Nice casual privacy increase too. ... and their behavior strikes me as a bit unethical too— wastes your resources, in order to compromise your privacy, which you can get back using a service they sell you. Lame.
So, yes, sure. It wastes resources but it's not a major concern unless its replicated by more parties.
The motivation you describe doesn't follow— any sane large miner does their mining from a shielded node with low degree— connecting only to their own nodes, other known miners and major nodes, and they separately run large public nodes.