Fantastic, almost unbelievable

This concept, having a common repo for blocks, accessible directly from WP admin, just like for plugins and themes, is the way to go. You can select exactly the blocks you neeed with a click and disable them also with a click. No need to have users see a lot of listed blocks that just happen to be installed by plugin that has only one block you really need.

Nothing is downloaded, they work from the cloud.

Can be network activated.

But more, as you can add local blocks that become visible in special tab on the Cloud Blocks activation/deactivation screen.

And you can contribute to the global repo through NPM.