Path-aware networking
The Internet Society's study is mostly about local traffic unnecessarily being sent out of a country to reach another ISP in the same country because of a lack of national peering. That's usually more expensive and introduces more latency than ISPs simply exchanging traffic within their own country, especially in particular parts of the world.
However, whilst the Internet offers ubiquitous access by design, there's certain data that should either not leave the country, or where it's not desirable for it to do so - for example, certain government, healthcare, military, or various critical infrastructure traffic. Even if it's encrypted, a hostile actor can still gain significant information from where traffic is headed to and from, and there's also the possibility of capturing the encrypted data and later being able to decrypt it in a post-quantum environment. Some data will still be valuable even years later.
This is why there's increased interest in path-aware networking (e.g. SCION, but there are other initiatives) whereby users or at least organisations can determine how their traffic is sent across the Internet - for example preferring routes within a particular country or region.