My opinion on this is that e-commerce is extremely competitive and consumers are already highly motivated to pay the least amount of money. If it were cheaper for consumers to go elsewhere they would, and sellers would follow.
Sellers are just complaining that they can't access Amazon's audience and do as they want. Luckily there's eBay, Shopify, Wix, etc. etc.
For one thing, how would you even right and enforce a law on maximum size/impact of a company? How would this even politically get through? There's already enough push-back against enforcing laws like "don't form cartels". The pushback on maximum size/impact of a company would be even more intense.
In any case, as the article states, "Today, Amazon tells sellers that if it detects a lower price for their products on any other online store, they will be punished, which is to say, their ability to get their products onto a place on the Amazon website where customers click will go away.". In other words, e-commerce is not extremely competitive.
This is a good thing, and those sellers can leave Amazon.
I’m not planning to leave Amazon, but I’d love to find good alternatives.
For more niche items I buy in bulk from different the manufacturer's site. To be honest it's a little more work but to help retailers it's worth it. Sometimes I have to pay for shipping but I do remember that I'm saving 130 dollars a year by not being Prime.