Most businesses have a commission structure set up to be simple and easy to understand, which helps it’s purpose, an incentive to salespeople. But most businesses aren’t that simple, and attributing the value of a sale to a salesperson is complicated. If you were just selling widgets through salesmen, and every deal was closed on a COD basis, and the volume and size of sales had no effect on production or other business operations, and the salesmen worked totally independently, and had no on-going service requirements involved in the sales, then a limitless commission would make sense. But that doesn’t happen too often.