Because you just described how a bunch of businesses can make money in a way "Blockchain" cannot. From a financial feasibility perspective, it only demonstrates that a decentralized store of information is going to be innately unprofitable.
Isn't that the whole point of the Bitcoins themselves? Without that incentive, storing the public, distributed ledger would be a thankless, expensive task. By incorporating the Bitcoin "reward", the miners are incented to maintain the ledger. It certainly appears to be working, looking at the current value of Bitcoin.
The parties that need a common ledger can do it jointly, with mutual mistrust. Think of ten big brokerages maintaining a blockchain for recording bond ownership.
This is a common error. The blockchain itself doesn't make money. Just like the internet itself doesn't make money. People build collaboration models on top of the communication protocols and they make money.
(You still need to pay the ISPs of course and eventually the ISPs become too powerful and start demanding bigger and bigger fees and then the whole thing turns to shit. See: Bitcoin, the internet.)
