I used the term calldata interchangeably with blobs, but this is completely irrelevant to my point. Blobs just made native Ethereum DA cheaper, it did not help the centralization issues. DA proofs on Eth still have many elements of centralization because you cannot easily verify that the blob corresponds to the root hash in the state commitment. You have to use KGZ commitment schemes (and zk magic) to immensely complex proofs systems of the fact that L2 state can be derived from L1 blob data.
Look at the complexity of optimism’s fault proof system for proving DA fraud:
specs.optimism.io/fault-proof/in