Because IDF doesn’t have full capability of Air-to-ground attack.
We use F-5 to train pilots before they join second-generation fighters flightline. Of course, air-to-ground attack training is very important in phase III of F-5’s training, IDF still can’t replace F-5’s training, and If we use IDF as training, We gonna need new fighters to maitain air superior. We wish to buy new F-16C/D Block50/52 in next ten years, it isi really hard to say this dream will or will not come true.