There's a tangent at the beginning of this video on the Epic of Gilgamesh briefly talking about an oddity where most ancient cultures have stories about the Pleiades star cluster, often describing them as sisters, and an aspect all the stories share is that there are originally seven, but one has somehow gone away. This is extremely strange, the video explains, because although there are seven stars in the cluster bright enough to be seen by eye, two of them are too close together to be resolved as separate unaided, so whoever originally came up with the story would be more likely to talk about "six sisters." The explanation proposed is that the story is so old that the stars' proper motion has hidden an originally more distinguishable seventh star.
Now, the video is sourcing information from a Phys.org article by the author of a paper about this idea, and the paper's abstract neatly sums up why it strains credulity - for the proper motion to be large enough, it needs to be so old that "these stories may predate the departure of most modern humans out of Africa around 100,000 BC." Part of the explanation offered is that it was preserved through the largely undisturbed Aboriginal Australian cultures, but that's still an unfathomably long time.
There is a preprint of the paper linked in the article and while the argument sounds sensible to me, I have no specialist knowledge and would like to hear a second opinion. Has anyone knowledgeable criticized or otherwise seriously responded to this idea? Is it plausible, or is there something wrong with the data that shoots it down?
Or for that matter, is my incredulity just a personal bias coming from being a Brit who's culture gets smashed to pieces and rebuilt half a dozen times before breakfast by comparison?