Blockchains are best fit for an environment where there is contentious data involved. Of an overall system, it is best to implement the value-bearing contentious part of it using a blockchain, not all of it.
A good analogy is to see the blockchain as a TEE. It can securely execute some code, and reflect the outcome on its state. Which parts of an application are best fitted to be executed on a TEE? some, but certainly not all.
Money is not the only contentious pirce of digital information that we care about. It is the most obvious one, though. Other examples that come to mind:
- All sorts of digital assets in games
- Sensitive personal identification data
- Valuable digital goods such as electricity, storage and bandwidth
- Knowledge and social graphs (the network, most valuable asset that big social media companies cling onto)
- And many more