Brand is a powerful defensibility, but it's fundamentally different from network effects. Like with scale, your brand defensibility is correlated with the growth and usage of your product, and so it's easy to confuse brand with network effects. However, they work very differently.

Brand arises when people know who you are and what you do. A well-established brand identity comes with psychological switching costs. People are less likely to switch to an unknown or lesser-known brand from yours because psychologically they will default toward what's familiar.

People tend to be risk averse and avoid the unknown. When you have brand recognition, people are familiar with what you are and what you do. That gives you a competitive edge. Brand defensibility is so critical in today's attention economy that, paradoxically, even negative brand awareness can help make your business more defensible (within certain limits).