Self-reports typically don't even count as one data point, because they're notoriously unreliable. Reports about one's childhood and motivations, doubly so. There's a reason psychology as a science is no longer based primarily on introspection, as it was in the 19th century.
Exceptions if people's self-conceptions are what is actually being studied; in that case collecting self-reports can be legitimate data-collection.
Exceptions if people's self-conceptions are what is actually being studied; in that case collecting self-reports can be legitimate data-collection.