Each of us does what makes us comfortable.
I do not pre-wash because I like the sizing in the fabric and life is too short to spend hours ironing and starching fabric before I cut it. I have never found anything bizarre in my fabric in about 55 years of sewing and I'm not going to start getting paranoid now.
However, every quilt I make is washed at least once, with colour catchers, before I give it away. I have a bunch of feline quilt inspectors, so cat hair is endemic in my house. Plus, I love the feel of a good new clean quilt before I give it away.