It can be one factor. It's quite common in areas such as IT services, where the expertise is in very short supply. Providing training to government employees in these sectors risks making them even more attractive to the private sector. That's one big risk. It explains why government departments have to use outside consultants.
I've discussed this with a couple of government deputy ministers. That's what they clearly told me, especially when it comes to IT. That is one reason that explains the use of external consultants, because it's very difficult to find that expertise, even if the government wanted to hire employees with that expertise.