Standardized APIs solve centralization. The use of Merkle trees to store way too much data and make a distributed computer slower than any individual node has nothing to do with that.
No, they don't. They still don't ensure data availability, consistency and you still have to trust the API provider, a third party. Web3 does away will all that. You just use the service.
Decentralization itself is what gets you availability, not the blockchain structure. A consensus algorithm is what gets you consistency, not a blockchain structure. There's no need to store your data in the most wasteful way to store data and perform compute to get these features.
The blockchain data structure makes the data it encodes tamper-proof. It makes historical data immutable, and it makes the current state of a system and the state transitions that led to the current state fully auditable in a shared-data context. These features enable applications that might otherwise incentivize illicit data tampering (such as applications that deal with asset account balances and ownership records) to be decentralized. I am unaware of another solution to this particular problem.
"Zero trust" is meant to refer to the data layer: because the current state of a blockchain system can be re-generated deterministically from the historical data—which is immutable and fully auditable—you don't have to trust anyone's version of the current system state, even if you are not yourself currently keeping a copy of it.
These technologies do not solve all of the moral and ethical problems that humanity faces, but I don't think anyone is claiming that they do. Blockchains don't stop people from deceiving each other, and they don't make people smarter so that they entirely avoid introducing bugs into their software, and they don't stop people from trying to steal from one another.
But they do make it possible to decentralize high-value data records that would otherwise need to live in high-security environments controlled by governments or well-capitalized businesses that would also need to be trusted 100% not to tamper with those records.
How does decentralization give you availability? You need a financial incentive to make data available, that's where the tokens come in.
Also stop conflating all crypto with scams, it's a moot point and borders on arguing in bad faith. People use good old money to run scams and rob people all the time. The fact that people use the tool with malicious intents doesn't detract from the value of the tool itself.
I personally don't care about DeFi, I only care about the technological aspect. The tokens are just a mean to use the decentralized service. And again, people misusing the tool does not detract from the merits of the tool.
