I found the blockchain use case flow chart here to be excellent. pg 42
"Are the entities with write access having a hard time deciding who should be in control of the datastore"
Because by definition, if the business practice exists in the first place it is because they already found a solution to collaborate.
I'm almost tempted to add a snarky: "for further information, please refer to this article: https://en.wikipedia.org/wiki/Law"
Do you know why these legacy methods persist? They persist not because the people involved don't know there's a better way. They persist because nobody can agree on who should control the new way.
This is exactly the problem that blockchains solve. This point is subtle, but it is extremely important, and it absolutely needs to be taken seriously.
I should point out, that Git solves exactly the same problem, by the way. You don't want a centralized entity hosting your project? Great, use git. Git, by the way, is a blockchain.
B) Git is perfectly secure if you don't accept pushes.
What git does not have is distributed timestamping, which is necessary for a currency, but not version control. And which is why PoW et al were introduced for cryptocurrencies. However, that is not a fundamental property of a blockchain, though it is useful for some (but not all) of the applications of blockchains.
Tell me, which of the conditions of the flow chart does git not satisfy? And better yet, which technical property of a blockchain does git lack that disqualifies it?
You seem to be trying to define blockchain as "a thing without a use case", and then when presented with a use case say "see look it has a use case! it's not a blockchain!".