It's easy to forget - but the information they collect can be used by the group that collects it, and by other parties (Gov't TLAs, hackers, insurance companies, banks, business associates, contractors, partner companies). This can happen now, or at some point in the future.
The data can be combined with other data, such as the National Insurance Database (which is illegal to publicly discuss), to draw conclusions about yourself - possibly based on untrue assumptions.
Master Data programs/systems/initiatives are consolidating, de-duping, and integrating data from disparate systems. It doesn't matter that you put down a fake address 100 times, you just have to put in a real address one time - these systems can collate all the data, validate each one against the USPS database, and toss the fakes.