And they can't on a Walmart owned database based system? You know the good old boring web application? HN is one example. Hundreds of people are using it, upvoting and commenting at at any given second. Works just fine.
Federated database systems are totally a thing also! It's not even that hard to set up a pub-sub system, service bus, or whatever. There's entire ecosystems of vendors that have turnkey or SaaS solutions in this space also.
People just forgot that these things can be done with boring old technology in the excitement of doing something hip and cool.
People just forgot that these things can be done with boring old technology in the excitement of doing something hip and cool.