In payment gateway integration, webhooks are usually considered a single source of truth for updating the payment status, with status check api as a fallback.

They are indeed everywhere, but it's possible you don't have a need for them. For example, every time you buy something online using Stripe, the seller receives a webhook indicating that a purchase was completed.

I receive webhooks all the time as ack that something was processed/ or a notification of the status of some sort of thing in an external system that we don't control.