I've purchased patterns from etsy sellers who explicitly say that patterns are for personal use. Later I buy a related book and the exact same pattern is in the book, exactly the same. I have purchased sewing patterns and browse etsy and the EXACT item down to the decoration is being listed as personal use only, copyright by seller. I'm like WHAT!
I am ready to disregard these statements since the copyright of the book, and patterns predates their supposed ownership of the pattern.
Unless they invented sewing or crocheting, etc., I don't think it's a big deal. How can they prove they didn't copy it? How can they prove you or I copied it?
Chrysler, Ford, GM, Toyota all sell cars its fair competition.