>>96263791
I mean if we start referencing one of the most peripheral and obscure elements of a publication, and it becomes popular online, maybe as a meme, the likelihood that new authors reference it increases.
And at that point it wouldn't necessarily be a "reintroduction" or "the moment it becomes canon", it would in fact be a callback to old obscure canon.

I don't believe that unknown and obscure tidbits of lore are outside of canon until they are acknowledged widely.
In fact I think it's the opposite: unless they are retconned or amended directly, they remain floating in a dark corner of canon (inside of it).

The thing I posted as a picture is canon, the mechanoids of El Drongo are canon.

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This is in fact important, because Games Workshop published on the Old World website a map of Estalia, believing it to be such an old obscure tidbit of canon lore.
Instead, it was outside of their ownership, a fan creation. They had to hastily remove it to avoid lawsuits.

If that map was in the Citadel Journal, or in a late Town Cryer, they could have kept it instead.
Now there's the distinction between "official canon" and "non-canon", a real legal distinction.