If you want to Praise that, just so you can save a few pennies,for giving up the quality, then so be it...
The problem with your theory is that Americans voted with their pocketbooks. Walmart wouldn't have gone anywhere if people hadn't fed them. Mom and pop couldn't compete because people didn't want to pay more for the same goods. Mom and pop needed to face reality and diversify and offer alternatives. Like better quality merchandise. Some did, some survived, others, not so much.
The middle class goes down when the economy goes down and visa versa, but again America voted for their pocketbooks to get what they could instead of sound fiscal policies.
Walmart appears to be your bogeyman.