My take is that the Signalgate thing was mostly about usability[1]. Which I suppose could be considered an implementation thing but is something that should be explicitly addressed. So a possible NSA based conspiracy theory here is that NSA is working in the background impairing usability.
Cryptographic libraries are not always documented as well as they should be. In the case of something like Python, it is not always easy to map library documentation to the resultant Python.