My problem is when the oligopolies hurt the market with these practices. I used to buy boxes of nitrile gloves from Home Depot for painting. Then they started

My problem is when the oligopolies hurt the market with these practices. I used to buy boxes of nitrile gloves from Home Depot for painting. Then they started carrying 'HDX' brand nitrile gloves. Then they stopped carrying all other brands of nitrile gloves. I'm not sure the practice is the problem, or the oligopoly. I would shop somewhere else, but where am I going to shop? Lowes?