Do I really need a CRM for my business?

I work for a web hosting company, and they are considering implementing CRM tools to expand their business. However, they are uncertain whether they actually need it, given that they already use a billing tool (WHMCS) that covers many aspects of CRM such as client management, ticketing, invoicing, and various other functionalities. So now the question arises, besides these functions, how can a CRM benefit this business? Thank you.