Scalability
To couple educational institutions and services, frequently a peer-to-peer approach is taken – for institutions usually be establishing some sort of secured web services, and for services usually with tool interoperability. These solutions only depend on bilateral agreements instead of any governance model, but unfortunately the number of such interfaces can grow quickly – with n being the number of institutions, on the order of n2 interfaces have to be established and maintained.
A centralized approach only requires n interfaces to a central hub, which routes data or – as in some approaches – is supposed to provide centralized data storage. A problem is that this structure establishes a central point of failure and also a centralized point of attack.
For a self-sovereign ecosystem, on the order of n agents need to be established, i.e., it scales the same way as a centralized system.