From Wikipedia:

Brushing is a deceitful technique sometimes used in e-commerce to boost a seller's ratings by creating fake orders. Sometimes a seller will do this by paying someone a small amount to place a fake order, but sometimes the seller will just use another person's information to place an order themselves. Because a shipment usually has to take place for an order to be considered valid, the seller will frequently ship an empty box or some cheap item. These fake orders, if unnoticed, can boost the seller's rating, which can make it more likely that their items will appear at the top of search results on e-commerce sites.

Many e-commerce sites have recognized the problem and claim to actively combat brushing. One company that has received a lot of attention is Alibaba, and in the prospectus they published before their Initial Public Offering they even mentioned the problem. Brushing also inflates the numbers reported on a company's financial statements, and therefore, it also attracts the scrutiny of investors and market regulators. For instance, the US Securities and Exchange Commission opened a probe to investigate the validity of their data when Alibaba reported revenue of more than $14 billion on Singles Day.

Good article: https://www.forbes.com/sites/wadeshepard/2017/11/27/americans-are-receiving-unordered-parcels-from-chinese-e-criminals-and-cant-do-anything-about-it/

Makes you think twice when you give your address to random Chinese seller. Brushing itself is kind of harmless, but if the seller is willing to abuse your address for brushing, what else the seller could abuse it for?