why is insersional inactivation better than inactivation of anitbiiotic to select transforments

In insertional inactivation, a foreign gene is inserted within -galactosidase gene, the enzyme -galactosidase gets  inactivated. Then the bacteria are grown on a chromogenic substrate. Non-recombinants will produce blue-coloured  colonies. Recombinants will produce colourless colonies. So, recombinants can be easily distinguished from  non-recombinants. 

While in antibiotic resistance,a  foreign DNA fragment is inserted within the tet^R gene. Hence, tetracycline resistance is not present in the recombinants. So, recombinants will grow on the media containing ampicillin, but will die on media containing tetracycline. On the other hand, non-recombinants will grow on medium containing ampicillin as well as on medium  containing tetracycline. So, this method is comparatively difficult than insertional inactivation.