Usually the burden to approve an Ad is on the network that hosts/serve the Ad. Google does require approval for all Ads you want to serve to Google Search or Google Display Network, as well as Ads you want to sell through Doubleclick Ad Exchange.
Doubleclick is actually a suite of different applications.
I suppose you mean DFP (Doubleclick for Publishers). This is a google product but it doesn't necessarily display ads from Google Network. With DFP you can show ads from Google but also other networks or even your own negotiated ads. So in other words even though it's a Google Product it's designed to give publishers freedom on which ads will be displayed. If you use DFP to only show ads from Google Network such as adSense you can rest assured these are reviewed by Google for such social engineering tactics.
I suppose they might block sites that use DFP to serve ads from other networks they can't vet and don't go through good review and were detected to contain bad Ads.
Doubleclick is actually a suite of different applications.
I suppose you mean DFP (Doubleclick for Publishers). This is a google product but it doesn't necessarily display ads from Google Network. With DFP you can show ads from Google but also other networks or even your own negotiated ads. So in other words even though it's a Google Product it's designed to give publishers freedom on which ads will be displayed. If you use DFP to only show ads from Google Network such as adSense you can rest assured these are reviewed by Google for such social engineering tactics.
I suppose they might block sites that use DFP to serve ads from other networks they can't vet and don't go through good review and were detected to contain bad Ads.