I think it's a little more specific than "people don't perform well under stress." A software development job may well entail stressful situations—for example, "The founder got interviewed on Oprah and the servers are melting!" But that kind of stress is different from a interview stress. There are definitely folks that will step up to the challenge of melting servers, but go to pieces under the social stress of an interview.

Now, maybe getting into the biological mechanism by which they go to pieces is too specific, and trotsky could have communicated more effectively by eliding it. But it's an important point, and I don't think it reduces to just "people don't perform well under stress."