Who spoke of "a single miner"?

Understand that the miners have to some extent the ability to maintain a certain illusion of decentralization.

I don't propose that bigger blocks will immediately translate to consolidation of miners in hashing power (what the user is really worried about) but it certainly leads to risky behaviours that reduces the security of the network. The cost externalization to nodes is not something most regular users would think twice about yet it severely undermines the nature of Bitcoin.