Yes of course they did. How do you think Walmart got so big?
You want to talk discount mass, compare Sam Walton’s Walmart that prided itself in carrying American made goods. Multipacks and polybag programs existed then too. They were no cheaper after than before. Where cheaper did arise you’ll find lower quality goods. Those Polos you find at TJMaxx aren’t the same as the ones in Macy’s, they were made to spec to be sold at that price with a specific margin requirement at a specific retail preprice.
Walmart got big because it revolutionized retail trade and introduced data management on a very large scale.
Walmart knows to extremes what customers want and then provides it
There is a near Biblical acceptance here that Walmart sell China junk and that is not true. Walmart buys world wide, including the USA. It canbe argued that most of what Walmart sells is of USA origin.