I'm not aware of any persuasive evidence that Cambridge Analytica had much of a political impact. If you have some please send it my way.
I agree, microtargeting would be most useful in politics - much more than commerce. Of course political campaigns would want to use anything claiming to microtarget.
But my understanding there also is that the verifiable impact is minimal and the most standout campaigns rarely if ever cite Facebook as the differentiator.
@nottrobin @res260 @bagder
First link on a search engine:
https://en.m.wikipedia.org/wiki/Cambridge_Analytica
The section is titled Elections, and from there you can scroll the subsections by country.
There are dozens of references if you’d like to check sources.