Data is used to make good, informed decisions, and data is used to develop financial statements where the government is accountable to the promises they've made. The financial statements then show you the actual result. Therefore, it's important that the data isn't compromised by an individual who shouldn't have access to it.
You want to limit who has access to what. People only need so much information to do to their jobs, so it is really just a best practice that you should make sure that those who have access have the right access to the right information and only when they need it.
We've talked a lot about data quality, and this is the entry into good, proper data quality, because good data allows you to make better-informed decisions.