Developing a Facebook chatbot with AWS Lambda and MongoDB Atlas allows developers to build scalable, responsive, and cost-effective applications without provisioning or managing servers. The integration of serverless computing with managed database as a service enables developers to focus on developing code while minimizing infrastructure management. By using MongoDB Atlas for data storage and AWS Lambda for serverless computing, the chatbot can be built quickly and efficiently. The chatbot's functionality includes sending weather queries through Facebook Messenger and storing message information in MongoDB Atlas. This setup also supports data persistence with the application and demonstrates how MongoDB Atlas can be used with other AWS services such as Elastic Beanstalk and Kinesis.