They don't have control over the supply of any particular good, it's not like an ISP where they have covenants with local governments that limit competition, they're not Standard Oil. They're not even at the level of Microsoft, because there's not much they can do to exclude competition.
But I guess some people have tried this tact, before. Here's an article which discusses many of the points you've made and explains why they don't make sense:
https://truthonthemarket.com/2006/07/10/the-unconvincing-ant...
Honestly it seems you either refuse to read what I wrote, or you are invested in a free market ideology. The link you posted is nothing more than a hard-libertarian free market fanatic opinion blog, heavy on snark and lacking in value.
Read about the damage Walmart does to communities and why even their mere presence in the market completely distorts it:
https://money.com/walmart-stores-closing-small-towns/
https://www.citylab.com/life/2012/09/radiating-death-how-wal...
https://popularresistance.org/new-report-wal-mart-destroys-l...
https://m.dailykos.com/stories/2013/03/28/1197622/-The-Walma...
This goes for all megamart chains, Amazon and the like, but Walmart is among the very worst.
As a consequence of this, local businesses die, jobs are lost and people either have to move away or accept Walmart jobs with well-documented bad pay and bad working conditions.
All of this is a deliberate business strategy by Walmart, because the US political climate and "business-friendly" ideology from both major parties prioritizes giant corporations with enormous lobbying power, over small business owners.
As a further local effect, business life is driven from the city centers to outside the cities, causing fewer people from the suburbs to go into the city centers, leading to urban neglect and decay.