“Do this” is advice. “Do this, and here is the thing everybody did until 2021 and why it stopped being right” is knowledge. The second is what a reader comes for, and it only exists if the abandoned position is still written down.
There is a sharper reason than pedagogy. A document that silently drops what it used to say cannot be checked. Every version of it looks equally authoritative, because the evidence of it having been wrong is removed at the same time as the wrongness. This is the specific way a “living document” goes bad: not by being wrong, but by becoming unable to be shown to have been.
Retirement therefore has to be an edit to a status, never a deletion — and the reason has to render where a reader meets the entry, not sit in a field that only the file’s author ever opens.
Applied here: Rejected and Superseded are statuses on a document that
keeps its body; retired entries appear in the generated index with their
reason in the status column; and a live practice citing a retired paper is a
lint finding rather than something to be noticed. The migration surfaced a
chain nobody could have read from the source data — a paper superseded by one
that was itself later rejected — which is exactly the shape of thing that
only exists if you kept both.
The corollary people skip: keeping the entry obliges you to keep it findable. A retired document that stays in the record but drops out of the indexes has been deleted in every sense that matters to a reader; it just still occupies a file.