There are a number of reasons why some people believe that Shakespeare did not write all of his plays. One reason is that there is no definitive record of him writing any of them. Although there are some documents that mention Shakespeare as a playwright, none of them explicitly state that he wrote any particular play.
Another reason why some people believe that Shakespeare did not write all of his plays is that there are a number of differences between the plays. For example, some of the plays are written in a different style than others, and some of the plays contain anachronisms (errors in historical fact).
Additionally, some people believe that Shakespeare would not have had the time to write all of the plays attributed to him. He was a successful actor and businessman, and he also had a family to support.
Despite these arguments, there is also evidence to support the claim that Shakespeare did write all of his plays. For example, there is a strong body of scholarship that supports this claim, and there are no definitive records to prove otherwise. Additionally, Shakespeare was a highly educated man, and he would have had the knowledge and skills necessary to write the plays.
Ultimately, the debate over Shakespeare's authorship is likely to continue for many years to come. There is no easy way to resolve the issue, and there is room for interpretation based on the available evidence.