When an account has multiple contacts, the platform today only marks one as ‘primary.’ There's no way to designate which contact is the billing contact (where invoices and payment-related emails go) versus the on-site contact (who the technician calls when they're on the way). For commercial accounts especially, these are typically different people: invoices go to payables@xyzbusiness.com, but the technician needs to call John Smith on his cell.
Adding a contact role on the account record (Billing / On-Site / Primary / Other, etc.) would let downstream behaviors default sensibly: invoice emails route to the billing contact, service-call notifications route to the on-site contact, etc. The data layer change is small. The value depends on the role driving downstream defaults — without that, you've added a label nobody acts on.
What contact roles does your shop actually use today, and which downstream behaviors should they drive? Drop a comment with your specific scenario — voting and comments here will help define which role types matter most and which defaults are worth wiring up first.