It is not incorrect. Witness data is designed to be fully discardable including from hoock files, while the OP_RETURN entry must be stored by all nodes in blocks forever due to consensus requirements. The only thing it is pruneable from is the UTXO set, which is no longer memory backed.
Discussion
But you need witness data when validating transactions.
Since opreturns can't be spent you should be able to get away without validating them.
But the OP_RETURN data is part of the main transaction hash, and by extension the block. You can’t “download a block but not the OP_RETURNs” without losing the ability to verify against doublespends and inflation.
You can however not download witnesses and the only thing you lose is verifiability of the execution path (and some data like HTLC preimages). But this data is not relevant to 99% of people, and even LN node impls, after 3 months.
We can use an assumevalid-type approach to skip witness verification .
Yeah valid point.