I don’t know whether that is true, but because I am lazy and because I rarely use anything other than boneless, skinless chicken thighs for Indian recipes, I almost always skip the marinating step, and the chicken is always perfectly tender. I have never noticed a big difference in flavor between marinated and non-marinated chicken, either (although this may be because the smaller chunks of thigh meat I use absorb flavor more quickly during the cooking process than bone-in pieces would, negating the need for pre-flavoring).
