Carb caps are an essential accessory for dabbing - whether you're a newbie or a seasoned veteran. If you dab without a carb cap, you’ll be pulling cold air into the chamber of your nail.
The air flow will cool down your heating element and concentrates before you are able to enjoy all of the flavors your concentrates have to offer. Dabbing without a carb cap forces you to take higher temp dabs. This destroys the terpenes in your concentrates. You don't want this.
When you use a carb cap, you are able to regulate the temperature of your dabs. Using a carb cap turns your heating element into a convection oven. You want this.