Becuase writing was one of the only ways of communication. When you have to pay for a stamp, that makes your way of communication limited. It would be like if you had to pay a dollar for every text you send. It makes it annoying and unreasonable. Hope this helps!
The stamp act was passed by the british parliament on march 22, 1765. The new tax was imposed on all American colonists and required to pay a tax in every piece of printed paper they used. ships papers, legal documents, licences, newspapers, other publications, and even playing cards were taxed. That's why.
