Why was Freud's theory of psychoanalysis discredited?

Id, ego, and superego are largely abstract constructs of Freud's imagination. There is little to no empirical evidence for their existence.

While they offer an interesting starting point for discussing behavioral concepts, they are not physical components of the brain which can be studied or proven to actually exist.

Freudian theory is still studied as the introduction to conceptual psychology but it is viewed in the abstract and only meant to invoke deeper thought. As a scientific method for application, there simply is no basis for its use.

Modern psychology takes a broader approach to analysis and attempts not to make suggestions to patients without a more precise and scientific understanding of potential behavior.

Freud isn't necessarily 100% wrong, he simply expressed his abstract theorems as facts, rather than as the springboard for conceptual discussion they are currently used for.

You can't state an unprovable opinion as fact and not expect criticism. His theory's are still interesting, his facts are merely unprovable as anything beyond abstract concept.