Well it does matter to Pakistan. The reasons are:
1. All international trade happens through banking channels. In normal cases, any exporter or importer does a bank transaction and it proceeds smoothly, however, in case of blacklisting, a normal transaction will take months as each transaction will be monitored by international organizations, which otherwise would have completed in 3 or 4 days. One can imagine, given such a situation who will trade with Pakistani traders.
2. Secondly, Pakistan heavily relies on foreign remittances, such remittances will be scurtinized very strictly, resulting in similar delays.
Paypal and amazon like companies are of not that siginificance, given Pakistan economic structure, their presence or absence wont dent Pakistan's economy, however, one must realize the above two points, especially the first one.