Not trying to me mean or ugly here but that has got to be the stupidest thing I've ever heard. Many of us use all types of cotton for sewing and quilting. Cotton is one of the most manageable materials out there. I just make sure to prewash my cotton fabrics before sewing and/or quilting with it.
Yes, you can use quilting cotton as apparel fabric. The main thing to remember is that quilting cotton tends to be stiffer than apparel cotton. It isn’t particularly soft and has a stiff drape. It works best when made into structured garments. The fabric is sturdy and holds up through many washings. In general, quilting cotton makes very casual garments and is utterly adorable when made into simple little girl dresses. You’ll find that sewing with this fabric is incredibly easy. It’s easy to cut, doesn’t slip and slide, it holds a crease and irons nicely. See why it’s popular with quilters and sewers alike?
Whoever is passing that information on that you can't use quilting fabric to sew clothes with knows jack about fabrics IMHO.
Personally I can't wear clothing that has a blend in it and has to be 100% cotton and everyone around here that I know of uses what is coined I suppose as quilting cotton fabric to make clothes as well.