Many of the native wireless cards used in commercial laptops are not capable of packet injection. While you won't need this to monitor network traffic passively, you will need that capability to perform any of the wireless attacks. Furthermore, some of the native cards have compatibility issues with Linux (i.e. driver support isn't great).
For this reason, many of the tutorials out there tend to stick with two well-known and reliable wireless network adapters:
Note: these are not product recommendations, rather frequently used devices in many entry-level wireless pentesting tutorials. I point them out for reference not recommendation. (Though I own -and use- both regularly).