"Your chatbot should be purposeful, reflective of your product’s voice, and simpatico with your users. One helpful design exercise is to produce an assistant persona and personality:"
For a business, a "chatbot" or any feature similar to it needs to do one thing and that is solve the users problem(s). If the user wants to do X within the app or learn about Y, the chatbot needs to help the user with that efficiently and better than a human can for the feature to be successful. The "chatbot having a personality" comes second to "solve the users problem."
If the users are completely happy with whatever chatbot they are using, then sure adding in some "personality" might be a good idea and increase engagement slightly, but a poorly-performing chatbot that can't help the user but has a personality isn't going to help the business at all.
For a business, a "chatbot" or any feature similar to it needs to do one thing and that is solve the users problem(s). If the user wants to do X within the app or learn about Y, the chatbot needs to help the user with that efficiently and better than a human can for the feature to be successful. The "chatbot having a personality" comes second to "solve the users problem."
If the users are completely happy with whatever chatbot they are using, then sure adding in some "personality" might be a good idea and increase engagement slightly, but a poorly-performing chatbot that can't help the user but has a personality isn't going to help the business at all.