think of it this way. fabric rags because it is woven.
t shirt fabric is knitted so no threads to come out and rag up. You could cut the edges of the tshirt fabric very narrow and it might give the appearance of ragging if you had other woven fabric underneith it. Then if there is a fusiable on the back that will effect the rag look.
I always consider the nature of the fabric when thinking about these things.