A lot of the younger players start right out on 5's and 6's and have no experience playing a 4 and when they do, the neck is so thin, they just can't do it. Again, I started at a time when there were no 5 or 6 string basses! I played a 4 from 1972 until around 1991 when I picked up a 5 from a store I was returning a piece of equipment and they only gave me store credit so I had to choose something else! I still switched back and forth so for me, I never left playing a 4.