I understand the full time engineer thing. But it was never explained to me at any of the places I have been at that it was a liability thing. At every place they thought we would leak trade secrets. Was always frustrating that technically we could never even contribute the most minor of bug fixes.

maybe it's a "blame" thing, but it's not a liability thing. Nobody ever got fired for hiring IBM*, but nobody ever got a nickel back either.

*IBM is a consulting firm now