To me they mean merely that other people have also looked at this project and found it interesting enough to star, so I might expect less resistance from others

To me they mean merely that other people have also looked at this project and found it interesting enough to star, so I might expect less resistance from others to using it if I too decide it's cool and want to use it. I wouldn't be comfortable inferring much about adoption from number of stars, based on my own starring behavior, which is often "this seems cool, maybe I'll look into it more deeply later".