The de-identification recommended was still useful as it did reduce risk, just not fully. That is that the data was rather close to fully de-identified; just not quite. The reduced risk is still helpful.
Alternative use-case segmentation could have been done. That is we could have created two sets of use-cases, that each targeted different elements while also not enabling linking between the two resulting-datasets. However this was seen as too hard to manage, vs the additional risk reduction.
Further articles on De-Identification