Were oracle/DB2 systems considered viable options back in the day? Obviously not for a small project, but a company like origin was quite successful then and would have had the capital to buy licenses.
Still tremendously expensive, and not as performant as keeping everything in memory.
The approach described is what people nowadays would call memcache, but the entire architecture is different because client connections are persistent rather than resetting every page load like the web. They just built a standard game server keeping everything in memory in the regular data structures. Fork-and-persist is a nifty way of using the operating system's copy-on-write functionality to checkpoint state.
