Retailers want to see which promotions belongs to 1 campaign like a folder for week 34 or the TV commercial for summer 2019. Now you have to go to the campaign form to see this but on the discount form in Retail module you cannot see this.
It would even be better to have a mother child relation in promotions. That you can tell which items and stores are involved in the mother promotion and than with the child promotion say which type of promotion does apply to which product. This is more common in merchandise systems for promotions and is missing by retailers