I'm not an economist but it's pretty obvious to me that walmartization is downstream of Financialization which is not inherently free market (its a product of centralized banking and interest rate and bailout policies)
Of course the things you mentioned further accelerate walmartization. But that's the chicken and the egg. The government does bailouts and prints cheap money because the corporations do exactly what I said: the winners (who arise naturally thanks to economies of scale) will put their resources into gaining these things.