I asked my Mom what they quilted with. She was a teenager in the '30s. She said they used all cotton when she started quilting, then during the war the cotton thread they could buy was terrible so they started using C&C cotton wrapped poly sewing thread but doubled the strand. It worked just as well as the old cotton quilting thread and lasted just as long. She's never used the waxed quilting thread.
I read an article not long ago about how many times we could wear clothes between washings. I don't remember the number but the gist of the article was that we wear fabrics out washing them more often than necessary and our fabrics (thread included) would last much longer if we washed them less frequently. Machine agitation grinds the fabrics, and dry cleaning solvents are especially hard on fabrics.