Unfortunately it's not a written statement ( you can imagine that nobody working at apple would publicly say a thing like that). And it's not a direct source either, so you can very well take that with a grain of salt.

Actually, I am still hoping that someone will contradict me by providing concrete example of apple software using core data though, because as i stated, i invested a lot in that technology for an important project.

I can tell you that many projects have used CoreData, and abandoned it in short order.

Largely because it is a complex beast that many don't bother to become familiar with before they use it. Perhaps that is damning enough.

Lots of SQLite and PLISTS prevail, perhaps indicating the domain of data that needs to be stored for your average application.