Here’s what is apparent;
-Some dreams are clearly meaningful. They are directly about things you’ve experienced, and involve people you know, or are about events you’ve experienced or are anticipating.
-Dreams have the capacity to integrate in physical stimulation. We’ve all experienced the sound of our alarm being integrated into a dream before realizing what we are hearing. Experiments indicate that sensation on our skin can also be integrated in on some circumstances. In this context dreams could be thought of as a mechanism to enable us to stay asleep while experiencing disturbances.
-We also have dreams which actually wake us from sleep (nightmares) so dreams aren’t exclusively to keep us asleep.
All these facts are acknowledged by Freud. He postulates that all dreams have some sort of meaning, or rather, all dreams are built of things in people’s memories, and thus contain some information about the minds of people who experience the dreams.
Freud tells us that universal dream symbol dictionaries are impossible to construct, because it’s not any particular thing that means anything, but the relationship of different things in the dream content in relation to the individual’s own history which create meaningful content.
The most common theory of dreams today is just that dreams are random neural firings, strung together by our brains interpretation after the fact. This isn’t actually incompatible with Freud broadest notions, if you say that the firing isn’t totally random, but actually has some rough pattern. The degree to which it’s random would explain why our dreams aren’t straightforward but instead have a difference between its manifest content and its latent content.
Frankly how Freud’s notion of therapy ends up treating dreams or association as a sort of ink blot image, who’s goal is to try to encourage the patient to reflect on their own mind, motivations, traumas, and so on.
If you read The Interpretation of Dreams I find nothing that a materialist minded, science oriented person would strenuously object to. There is a lot you can object to in Freud’s own practice, and his methodologies, but while I wouldn’t say Freud is ‘correct’, I don’t think he can be as easily dismissed as some would suggest.