I think if more couples went for premarital counseling, they would know each other better, in a way that would be more meaningful.
First of all, you’d have a birds eye view into whether the person you’re with is open to seeking guidance/help.
Secondly, an observer can sometimes point out patterns in communication that can lead to bigger problems down the line (ie: one person being mevater too often, compromising on very meaningful values, elements of an abusive personality (hidden sarcasm about one’s mate, passive aggressive behavior, ridiculing in a subtle way, a controlling personality). These are things that might make a person feel the shidduch is a bit “off”, but may be hard to identify, and might lead one to compromise.
People also walk away from a good shidduch out of fear. Though individual counseling might be called for in such a case, having a therapist meet and greet and get to know both parties can help them navigate through the challenges.