Why are search terms with sales negated?

If you use preset strategic objectives or create a Fully Managed Campaign using Mass Campaigns, you may find the negative algorithm negating keywords on search terms with sales.

It is due to negative rules such as [ASIN] Remove Search Terms with Orders

Such negative rules are often used together with import rules to control the advertising budget more efficiently. 

When the algorithms find a search term with orders, the import rules will create an exact, phrase, and broad keyword in each ad group, while the negative rules will create a negative keyword for the phrase and broad ad group.