> They keys are still generated and kept using software they wrote.

This is a prerequisite for forward secrecy, which is arguably much more relevant.

> It’s physically impossible to be given the wrong person’s key because you personally had to get them.

Does that matter at all if the (in your threat model non-trustworthy) software just exfiltrates all messages?

If you don't trust your encryption software, it's game over (unless it encrypts everything fully deterministically and you regularly audit its outputs).