Exact Role of Blockchain in Blockcert

I went through many documents but I am really confused and not able to understand the role of the BlockChain network (except it delivers the hash to the receiver of the certificate)

Can I achieve the same without using the Blockchain network? I think yes, because what matters it he generated hash, if I can communicate the same to a student without using Blockchain it will still be valid. Or I can bake this as a OpenBadge and issue that to a receiver and verify using OpenBadge verify process

Any comments or suggestion to correct me if I am wrong

The blockchain’s essential role is as a decentralized verification network, that cannot be easily tampered with or taken down. Unlike central authorities that are vulnerable to attack or disasters (of war, of nature, or technical), a decentralized network is far more robust.

From a technical point of view, the blockchain provides independent time stamping, which provides essential security benefits not present in traditional PKI infrastructures or baked badges. Here is a post that outlines the technical benefits in more detail:

Thanks will read

I am trying to understand in more simpler word

I know the hash and blocks created on Blockchain will help authenticity, but how exactly? if issuer organisation is no more, me as a recipient of the certificate can be sure my certificate is still verifiable ?

Yup, that is the entire point. Good Blockchains are decentralized networks, comprised of thousands of computers. That verification network is far more robust than a single institution, whether that be a single vendor, institution, or certificate authority. Think of it as an additional layer of security and convenience.