No wondering, I just assume that's the case. Like, whatever the Chinese equivalents of 4chan and pastebin are would be in constant discussion over the best ways to exploit that information. OPM is a big umbrella over the US Federal Govt. They even got biometric data in the form of fingerprints.
There are certainly worse things to breach but it's basically HR for the US gov't. Imagine your company's HR dept getting totally owned, then people using the CFO's data to get large loans, make harmful business deals or blackwash someone high-profile.