I'm not really sure that's true at all.

If all of my friends are using Uber and I'm using Lyft, I get the same amount of value out of Lyft whether anyone else is using it or not.

Now, there is some network effect with new drivers signing up for a more dominant platform, making it harder to use others. Since drivers can (and usually do, in my experience) sign up for multiple platforms. That effect is greatly diminished.

Im not talking about a onesided network effect. Im talking about indirect network effect concerning a two-sided market.

If more of your friends use Uber than Lyft, that suggests that there are more customers on Uber.

This means Uber is more valuable for the drivers as a platform.

This means more drivers will driver for Uber.

This means Uber has better availability.

This means Uber is more valuable to customers.