Bad data sneaks in long before anyone notices.
In every long-running SAP project, business rules end up scattered across user-exits, BADIs, and includes — each one a separate piece of code, hard to find, hard to change, impossible to govern.
Every new check becomes a development ticket, even when the logic is just a value list or a "must not be empty". And the data quality reports that do exist run hours later — by which time the bad record has already been used by downstream postings, IDocs, and replications.