Plenty of things are critical, but not core. I'd expect something outsourced to be defined as non-core, and also that is a very flexible category.
For instance, Google had egg on their face in a court case a while ago, because they accidentally produced documents that tended to undermine their case vs Oracle.
They didn't account for gmail autosaved drafts, didn't group them properly with the final email that was sent, and so they didn't claim lawyer-client privilege.
Unfortunately, as they say, "you can't unring a bell" and once Oracle and the court saw them, they didn't agree that they were in fact privileged.
Subsequently they outsourced legal IT to a greater extent, and I infer a connection.
I don't know from an insider's perspective what their reasoning was, but it seems to me that outsourcing forces people to be more explicit about information sharing and provides a buffer.
Like, the engineers must know about gmail, and the in-house legal staff must know about producing documents, and they assume too much common knowledge because they're under the same roof.
Whereas if you send documents elsewhere, then you know they know nothing about gmail, and they know they know nothing, etc. And if you send similar documents, grouping them together is a standard generic process that will be done on everything.
If this all seems rather far afield from aerospace engineering, well, it so happens that one of the companies (I haven't worked for them) that people outsource legal IT to is one of the largest and best known aerospace/defence companies (but not Boeing).
When I found that out, I was like "Ah...their core competency is...paperwork! Of course..."
