[mr_overalls]

At some point when designing a data store, decisions must be made with regards to memory layouts, integrity, transaction guarantees, ease of replication, etc. These choices typically involve reliability vs performance tradeoffs for various use cases.

I mean, you _can_ store graph data in a relational database, but its' not typically easy to insert or query, there are serious performance penalties, etc. Purpose-built data structures will always out-perform generic ones.