Separation of concerns or no, the problem with a single central datastore is that it will eventually become the bottleneck as you scale. This is really difficul

Separation of concerns or no, the problem with a single central datastore is that it will eventually become the bottleneck as you scale. This is really difficult to fix, not just technically but politically - as a central datastore grows, everything and everyone starts taking dependencies on it: reports, homegrown tools, documented troubleshooting strategies, etc. They become sacred cows of an organization. Not only will there be resistance to the idea of splitting out that datastore, but major investment will be required to do it - implementing all of that disconnected messaging stuff you're going to need, reworking applications/services to communicate that way, and handling eventual consistency - which is a tough sell when the app works "perfectly fine" except for that scaling problem.