Can this model be used for compartmentalizing transactions? For example, an organization could use the system for their own internal accounting without revealing for the outer world what is happening, but at the same time the outer world can be sure that whatever transactions happen inside that organization, all the transactions are valid. When the organization makes transactions with the outer world, everybody can trust that it's real money and not counterfeited inside the company.

This might be a good way to make blockchain privacy better: as long as all the transactions are saved to the blockchain, they can be tracked afterwards. But if the early transactions are not known, only the current state, the privacy of users is much better. Only thing that is known are the balances of accounts. Nobody can know if there have been only one transaction or millions (except the account owner).

For a Steemit-like system this could be used for group editing of posts. A small group collaboratively writes a post little by little, making "internal" transactions (not shown for outsiders). When the post is ready, it's published for the outer world and it pops up in a Steemit-like website. The advantage is that the system stores early drafts (as long as somebody is maintaining the compartmentalized part) so there is no need for backups. The same system is used for making early drafts and to publish the finished text which is great for the end-user.

BTW, does this system resemble Urbit? It seems to me that you have a similar kind of approach here.