I'm not sure how preventing any time sales helps sole proprietor shops, as big enterprise can simply sell barely above cost till they sink the mom and pops. If they are looking to protect the consumer a better tact is preventing the boost and cut pricing tactic to make a sale seem like a good deal.
So I guess no BOGO/BOGOFs?
You can totally do things like BOGO if you're selling things way above cost, or if you're not a reseller but the actual manufacturer of the good.
An example of this is take out pizza, which usually offers BOGO if you don't opt for delivery.
The Sales rule is usually about when you are just being a market maker and not part of the production process itself. Similar rules exist for things like book sellers (you can not discount the price of a new book by more than 5% of the MSRP).
There are exceptions for perishable goods and for products that have been rendered obsolete due to technological progress. I think there are some other force majeure exceptions.
It's a bit stifling, but it means that huge retailers can't destroy smaller businesses just due to their huge capital reserves. It helps to preserve competition in the retailing space. And worst case you just have to handle it for a couple of months.