Payment Pointers were designed with very specific goals in mind:
Unique and Easily Recognizable
Various standardized and defacto-standardized identifiers are widely used on the Internet today such as email addresses and social media handles. The Payment Pointer must be obviously unique so that it is not confused with another type of identifier and also so that other identifiers are not assumed to be Payment Pointers.
It should be easy for someone to exchange their payment pointer with a counter-party either by saying it, writing it down or sending it in a digital message.
The payment pointer should not be tightly coupled to a specific payment service. It should be possible for any new payment service to leverage payment pointers by implementing the Open Payments standard.
It should be simple for individuals or small companies to host their own payment service endpoints at a URL that can be resolved via a simple and easily recognizable payment pointer. Likewise, it should be possible for a payment services provider to host payment service endpoints for multiple entities without the risk of hosting them at endpoint URLs that conflict with their other services. To that end the provider should have the option of hosting different endpoints under the same domain and a different path or at a different sub-domain for each user.