I am sympathetic to your argument, but it would be stronger if you didn't project the "why" onto a large group of people. It's pretty clear that the reasons are complex, nuanced, and possibly only a problem at scales most of us never encourage. (I think there are probably also benefits of the large size, e.g. Walmart has completely changed what you can buy for low prices, which has incredible value to many people)
Also, I'm not sure the SPOF problems are a result of anti-competitive behavior - AIUI, it's because JIT delivery between different entities is far more cost effective, and the human brain tends to ignore hidden risks.
