Probably less than 1% of developers have GitHub repos and there's no correlation between skill level and having a GitHub repo.
If you have extensive and current open source contributions, for most people it means you're unemployed, or you're violating your employer's contract terms.
Evaluating a GitHub repo for a summary of skills in not a trivial task, as scanning a resume is.
When all of your work is online, it suggests you are not spending much time contributing value to whoever is employing you.
Companies that can't find developers often have bizarre and useless criteria such as "must have GitHub repository" or "must have LinkedIn" or "must have FaceBook", none of which is correlated with ability.
We hire lots of capable people without GitHub repositories.