Not everyone belonged to a user group, which is where Apple allowed system software distribution until 1992 or 2001, depending on which way you look at it. (System 7.1 was retail-only and in 2001 Apple banned freely distributing older versions of the software--remember when Mac512 had to take their stuff offline?)

System 6 was also available in a box. I remember seeing it in old catalogs even after System 7 was out. I think it had the Scrapbook on the box.