From a financial incumbent point of view, if you are going to mutualize infrastructure, you need to actually mutualize the infrastructure. This means solving the game theory problem of accidentally giving away the value of your back office systems to your biggest, best-funded bank competitor -- not a competitive equilibrium. To that end, technology companies are a natural place for maintaining crypto systems. However, note that public chains today already have the benefit of billions of dollars in cyber-security spending (i.e., mining) and the dedicated engineering of thousands of open source developers. By choosing to use a public chain, you get this out of the box. With a proprieraty solution, even if the end-results are open-sourced, community is impossible to replicate. Maybe this is why IBM bought Red Hat for $34 billion, and Microsoft bought GitHub for $7 billion.
