Technically, binding isn’t required to authenticate Macs to Active Directory.
However, many network administrators use Active Directory (AD) as a “source of truth”. Computers and their MAC addresses are part of the computer record created when binding. As part of additional security, the network administrators configure the Wi-Fi systems to refer to the AD computer record to confirm the computer attempting to connect is owned by the organization.
The need here for binding is being imposed by your network admin.
