wouldn't you just put all those things into a contract and put the contract into the blockchain along with their signature as proof?
You seem to be arguing that blockchain has to magically solve real world physical problems, but paper contracts don't do that either. You still end up in court. Its just a question of how you are substantiating they really signed the contract.
No GP is arguing that since the blockchain cannot solve any of the mentioned problems, it does not provide any real benefit. The dispute for companies today are seldomly about whether they signed a contract (the part the blockchain could help settle - though you still need to provide the legal entity -> cryptographic key mapping) but how to interpret the contract and align the legal world(words on a page) with the real world (widgets delivered, machines broken, etc.).
If the problem was about enforcing a signature, you do not need a blockchain, each party to a contract can just store the cryptographic signature themselves or with one or more trusted custodians. That is a fundamental feature of cryptographic signatures not blockchains. And then you need some mapping from legal entities to public keys, but this might as well be a centralized database run by the government (potentially outsourced to a private contractor), after all in many jurisdictions the government already keeps a list of legal entities and metadata about them.
You seem to be arguing that blockchain has to magically solve real world physical problems, but paper contracts don't do that either. You still end up in court. Its just a question of how you are substantiating they really signed the contract.