I think Github is a tremendous resource, but while Github profiles can give a positive signal, they are not sufficient for negative filtering.

Many, especially older developers it seems, only begrudgingly have a profile for tickbox judgments encountered during job seeking. The best developer I ever worked with just didn't care about bothering with a Github profile, and the worst guy I ever interviewed had an expansive profile, including a repo with 80+ stars that was trivial and terribly coded, and our team's conclusion was that he got his bootcamp associates to star it.

At the end of the day it's a private company seeking a profit, and it's a little ridiculous that it's become defacto mandatory for proving you are a good developer, in the same (somewhat annoying and unfortunate) way that FaceBook has become defacto mandatory for proving you lead a social life.