Why did Jean-Jacques Rousseau criticize Jean Le Rond d’Alembert’s proposal for a theatre in Geneva?

Jean-Jacques Rousseau criticized Jean Le Rond d’Alembert’s proposal to erect a theatre in Geneva because he believed the institution would be harmful to the city’s innocent community.1

In his work Lettre à d’Alembert sur les spectacles (1758), Rousseau argued against the introduction of a theatre, viewing it as a corrupting influence that threatened the austere morals and Calvinist traditions of Geneva. His opposition was part of a broader defense of the city's character, which he felt was being undermined by the laxity and worldly values promoted by the philosophes of the Encyclopédie.12