What Manning did was absolutely damaging just harder to measure.
We do know that BinLaden had that information in his house so clearly he deemed it useful.
How do you count such instances of raids, rescue missions not performed because informants lost confidence in our abilities to keep their identities confidential?
Less tips= less action= potential for lost lives due to action we could have taken but didn't.
Manning's incident was not an "oops" moment, he didn't release one item he had a problem with, he clearly and intentionally tried to do as much damage as he possibly could.