Knowing SEO's history is not nostalgia. It is a pattern-recognition tool that tells you which new tactic to ignore.
The cycle repeats with new nouns
A signal gets discovered. It works disproportionately well. It gets industrialised. The engine devalues it and penalises the industrialised version. Keyword stuffing, link directories, article spinning, exact-match domains, guest post networks, and every AI-generated content farm since — the same arc each time, over roughly three to five years.
Where the tactic sits on the curve decides your risk
Early on a curve, returns are high and risk is low. Late on it, you are buying a liability that has not been repriced yet. The uncomfortable part is that the tactic still works right up until it does not, so performance data alone never tells you where you are.
The test that has held up
Ask whether the tactic would still be worth doing if the search engine could not see it. Genuine expertise, a faster site, a page that answers the question properly — all pass. Anything whose entire value is the signal it emits fails, and everything on the list above failed it at the time.
What this is worth in practice
It is an argument you can make to a client or a board before spending budget, rather than an explanation you give afterwards. That is the difference between strategy and hindsight.