There's a critical mass component to the companies you listed....

There's a critical mass component to the companies you listed. As in, they rely on the network of people who are already on it. That's the difference.

I think it comes down to how customers are actually using the service. I always assumed most sales of Afterpay were coming via the stores checkout process... as in the customer wants something, they go to the checkout and then they see Afterpay is available and use it. In this scenario the service is very easily substitutable. If i'm wrong and the vast majority of people are using the service differently then i'm probably ill informed.