"Trusted" is the keyword.
I remember some discussion about how Hillary, for all her power, had her IT run by that moron who was asking how to use BleachBit on Reddit. The election leaks showed how incompetent the entire DNC was with technology. The thing is, these politicians have very few people they can trust, especially to take care of their personal computers, emails, etc. Usually they pick someone like the child of a college frat brother or someone who's been working for their family forever. It has to be a person who's joined at the hip to them or who they have solid blackmail material on so they can be certain they won't leak secrets.
Also, politicians don't know anything about computers and don't know how to verify that the person they're hiring knows what they're doing. They also have little understanding of the dangers of technology use - they know that information can be stolen by hackers, but they don't know how that works and what things pose a risk. So a lot of them end up leaking sensitive information, because as politicians they can't avoid using modern communication technology and there are few people they can trust to manage their use of it.