There are tremendous advantages to a “three fingers under” string grip for beginners. Its only disadvantage is a loss of distance/cast. Consider the photo below.
This is Christine Bjerendal of Sweden. She competed in the 2012 Olympic Games (London) and she is currently competing in this year’s Olympics. Please note string grip.
Yes, there is a loss of distance/cast with this grip but there are also offsetting positives. Just because we start beginner’s with this string grip does not make it a “baby grip,” a grip adults would be embarrassed to use.