Richard Rutt has a great deal to say about the history of sock knitting, as well as knitting in general. I believe people constantly made socks, both for the family and for sale. It could be that sock making practices migrated to garment making. Creating a sweater is a special occasion, and extra expense of time and material. Perhaps a new baby or an evening out. You would also want to make a fine fabric if you were layering, as in a twinset, a suit vest or a pullover.
James Norbury's book is a faithful reprint of vintage patterns and easily available at Indigo
Mr. Norbury is an advocate of the back stitch, rather than the whip stitch. Bernadette Banner, a historical sewist makes the distinction of seams that will be stressed, as in the shoulder area, verses seams that only need to join fabric as in a skirt side seam. Alabama Chanin, a modern hand sewer uses Coats Button and Craft, a super strong thread doubled.
Oversewing stitch is common in English Paper Piecing Patchwork. The pieces are butted up against each other, joined, and lie flat when stitched together.