You can absolutely use poly in your piecing and quilting if you want to. However, you need to give it more give by fewer stitches per inch and/or looser tension. This avoids that problem that some quilter's reported of the thread 'slicing through' the cotton after some years of use. I PREFER cotton, but I've received from very valuable tips from quilts with many more years of sewing than I. I also found out that some threads that produce no lint in my Brother, produce tons of lint in my Bernina and visa versa. So, it could simply be how your machine runs on a specific brand of thread.