I know that the star is a de-facto way to calculate the popularity of particular repo. But, let me put aside this calculation for a moment, then I myself have stats around 250 repos and more than 40% of it, I have starred just because to refer it sometime later, not because I like it or love it, just for future ref., when I have to work on something that might need help or ref. from that particular repo.

So, if there is something that have a way bookmarks the repo then chances are hight these repos have lesser stars. Also, there is popular trend nowadays I see that 100 other developers have starred one repo for some particular reason that chances are hight that other 5 developers might star it because they just follow the developer, who have starred.