What is the key force of «وَلَيْسَ بِأَبِي وَائِلٍ»?

Narrator Criticism: Al-Mughīrah b. Saʿīd, Shaqīq and Jābir al-Juʿfī

• It identifies Abū Wāʾil as this same Shaqīq
• It identifies Abū al-Aḥwaṣ and Shaqīq as one person
• It applies the criticism to everyone called Abū Wāʾil
• It prevents confusion between two individuals named Shaqīq