The Pleiades are the most widely storied object in the sky and it is worth asking why, since they are not conspicuous by brightness. Three properties account for most of it.
First, they are a genuine group. Almost everything else in the sky is a chance alignment of unrelated stars at different distances; the Pleiades are a real open cluster, physically associated and close together, and they look it. A tight knot of points reads as a thing rather than as a pattern.
Second, they sit near the ecliptic, so the moon and planets pass close to them and they are visible from nearly the whole inhabited world, north and south. A figure at the celestial pole is invisible to half the planet; this one is not.
Third, their heliacal rising and setting fall usefully in the agricultural year across a wide band of latitudes, which is why so many calendars are pegged to them.
The recurring detail that seven are named while six are easily seen has invited a great deal of speculation, including the suggestion that the stories preserve a memory of a star that has since faded or moved. That is not demonstrable and the atlas does not assert it: seven is a common ritual number, and the eye under good conditions does get more than six.