People often try to claim blockchain use cases without much deliberation. Here is a condensed, quotable version of «Hitchhiker’s Guide to the Blockchain» and «Data lifecycle questions, not only for Blockchains».
Blockchain is an append-only database where mutually mistrusting entities all have to be able to edit every record.
There are some more properties, such as, generally, an unspecified group of entities, public visibility and immutability (some of which follow from the above). More information and background in «Hitchhiker’s Guide to the Blockchain» and «Data lifecycle questions, not only for Blockchains».
The following statement can be seen as kind of a corollary to the above.
Blockchain is too complicated and inflexible for most applications, as it is a specialized solution to a very complex problem, which is unlikely to occur outside decentralized cryptocurrencies.
Tiny simplifications of the problem result in massively simpler solutions.
We can learn a lot from the blockchain experiments, predecessors, and alternatives; most often, you will, however, want to have a smaller, more manageable subset of blockchain functions, such as transparency (not immutability) or consistency (not consensus). A lot of this can be flexibly achieved with timestamping and is also easier to fit into existing legal frameworks.