Was it ever a good metric? A star from another account costs nothing and conveys nothing about the sincerity, knowledge, importance or cultural weight of the star giver. As a signal it's as weak as 'hitting that like button'.

If the number of stars are in the thousands, tens of thousands, or hundreds of thousands, that might correlate with a serious project. But that should be visible by real, costly activity such as issues, PRs, discussion and activity.

There was a time when total number of hyperlinks to a site was an amazing metric measuring its quality.

There isn't just "good metric" in vacuum - it was a good metric of exactly the popularity that you mentioned. But stars becoming an object of desire is what killed it for that purpose. Perhaps now they are a "good metric" of combined interest and investment in the project, but what they're measuring is just not useful anymore.

A repository with zero stars has essentially no users. A repository with single-stars has a few users, but possibly most/all are personal acquiantances of the author, or members of the project.

It is the meaning of having dozens or hundreds of stars that is undermined by the practice described at the linked post.