A title company's promise to insure real property titles/deeds comes with many (sometimes pages) of exceptions or disclaimers that depend on the state of the title history. Stuff they don't understand (confused records, muddled divorce/death histories, old easements, etc.) they will disclaim from the coverage.
Title companies provide a several page title commitment that describes the state of the world as they see it and given that state-of-the-world they craft and issue a policy. They don't guarantee against things not included in the title commitment they disclaim them away.
In most cases, especially in developed urban areas, the default works. But if there are edge conditions, the title policy often doesn't fix them because the policy disclaims around them.
But if you read and understand the title commitment and trace the title history yourself (or hire lawyer to do so), you can challenge the title company to remove unwanted disclaimers or add additional protections before you close. Also, you can identify potential chain of title issues and have the seller fix them before closing.
edit: s/misstated/overstated/
As I understand it, the title company reviews and insures everything related to the title. And the Purchase and Sale agreement is a standard form contract. What would a buyer need a lawyer to review?