It seems more a marketing strategy than a real belief in user privacy. For example, see the latest rejection of ad-blocking VPN apps from the App Store
https://9to5mac.com/2017/07/15/apple-reportedly-shifts-app-s...
Regarding ad-blocking VPNs, I can see why one might be sad to lose these and disagree with Apple's move here. But it's not a privacy decision - it's an ad-blocking decision. VPNs actually focused on privacy, like privateinternetaccess, aren't being removed from the App Store.