Now, how to do with just JOINs?

polypeptides_missing_product.names

SELECT f.feature_id
  FROM feature f
       JOIN cvterm ON f.type_id=cvterm.cvterm_id
 WHERE cvterm.name = 'polypeptide'
   AND f.feature_id NOT IN (
        SELECT f.feature_id
          FROM feature f
               JOIN cvterm ON f.type_id=cvterm.cvterm_id
               JOIN featureprop fp ON f.feature_id=fp.feature_id
               JOIN cvterm gpn ON fp.type_id=gpn.cvterm_id
         WHERE cvterm.name = 'polypeptide'
           AND gpn.name = 'gene_product_name');