The IRS has our PII, but lots of it is not in a big bucket, it's quite diffuse. If PII is dynamite (and it is) then we want it divided up in silos, with firewalls, and limited access where nobody has universal access. Ideally a lot of it is protected by differential privacy - if I am getting audited, the auditor only see's my returns and not my identity, and someone else gets only my identity.