Those agencies are under the executive branch, and its been made very clear in the past that they prefer sneaking in backdoors to valid best practices.

The NSA sabotaging the Elliptic Curve method of random number generation used in the RSA algorithm comes to mind. They would otherwise be THE experts to trust, but lets look at the others:

FBI - Waco, Ruby Ridge, planned to assassinate Martin Luther King and so many others. CIA - promotes fascism internationally, causing all sorts of chaos in Latin America and the Middle East. Ever wonder how Komeni's faction overthrew the Shah? The CIA decided he had gone soft.

Germany is so trusting of the US on cyber-security measures that their government has been trying to ditch Windows for over a decade.

TL;DR: In the US, government experts do NOT have your personal security best interests at heart. They can and will use any dirty trick possible to spy on and control both our own citizens and those of other countries. Last authories that anyone should trust.

https://blog.cloudflare.com/how-the-nsa-may-have-put-a-backdoor-in-rsas-cryptography-a-technical-primer