They already do.

And anyone selling through any platform where they've all data let it be supermarket chain or e-commerce platform, should understand the risk that their data can be used to compete with them if you realize risk is not worth pay off, prefer selling on own website - it's not hard these days. No I mean, yes it's still hard to get eyeballs on your product but to list in Amazon, you need to pay Amazon tax.

The difference is that Amazon said they don't use third party data to boost their own sales.

In traditional retailers like Costco, if you are a product maker and supply Costco, you don't own any data from the sale of the product--Costco owns that data. In fact, you will have to pay for that data from data brokers (Retail Solutions Inc for example) if you want it.

Difference is that sellers have options because none of these are monopolies. It's not abusing your size at that scale and thus not antitrust. The same rules don't apply to everyone because not everyone owns an entire market.