Sometimes, companies are worried about "reusing personal GitHub accounts", but contributing source code or reviews with an already existing account does NOT mean that
-
existing ssh keys or personal access tokens would be valid to access your enterprise organization (all credentials would have to be authorized: https://help.github.com/en/github/authenticating-to-github/authorizing-an-ssh-key-for-use-with-saml-single-sign-on)
-
email notifications would go to any personal email (you can enforce the use of a company email domain: https://help.github.com/en/github/setting-up-and-managing-organizations-and-teams/restricting-email-notifications-to-an-approved-domain)
-
contributions could not be marked to belong to your organization explicitly (you can explicitly mark contributions to be done on behalf of your company: https://help.github.com/en/github/committing-changes-to-your-project/creating-a-commit-on-behalf-of-an-organization)
-
you could not enforce any merged commit to satisfy your coding standards an