Crazy quilts use all kinds of fabrics. Many people use different kinds of fabrics. Many years ago people used what they could get, they didn't run to the store to purchase fabric.
I only use cotton, denim, flannel, and fleece but that is what I buy when I need fabric. Silk makes gorgeous quilts, but I have never used it because of the price. I wouldn't use knit because personally I don't want to deal with the stretchiness. My first quilt was a stack and whack with a cotton and a poly blend. It was okay I just don't like the boring colors in it.