Each of us is a primary source for our arguments. They stand or fall on their own merits. If you believe an assertion of fact to be in error, then primary sources become more important.
But even primary sources are not without error, as witnessed in the current trial where a superintendent fails to recall something that happened in a meeting, even though his own notes recall the event.
The source is not as important as whether an argument stands up to scrutiny.
Humans are not apes.