The most important aspect of blockchain that is relevant here is that your counterparty half a world away and you both agree that you trust the state of this blockchain, and thus can transact on it.
For business running the same code on their 1 node instead of N is not a replacement, because their counterparty has no reason to trust whatever is running on that 1 node.
Your reasoning re: N nodes are expensive is also flawed. Executing a single payment transaction takes a fraction of a second of compute. Even if it is replicated 10,000X, it's still extremely cheap compute-wise. The low cost of transactions has nothing to do with subsidizing.
For business running the same code on their 1 node instead of N is not a replacement, because their counterparty has no reason to trust whatever is running on that 1 node.
Your reasoning re: N nodes are expensive is also flawed. Executing a single payment transaction takes a fraction of a second of compute. Even if it is replicated 10,000X, it's still extremely cheap compute-wise. The low cost of transactions has nothing to do with subsidizing.