Don't know why you are being down voted, but you should understand its about tradeoffs.
If I want to increase my database performance I can either
1.) Build this plugin and integrate it into my already working ecosystem
2.) Spend time researching, testing, and deploying VoltDB.
Given the popularity of postgres, and the relatively low friction solution of (1.), its clear why this could be an adequate solution. Sure you won't be as fast as VoltDB, but as an outside engineer we don't know the potential customers requirements, and if being as fast as VoltDB actually matters.
If I want to increase my database performance I can either
1.) Build this plugin and integrate it into my already working ecosystem 2.) Spend time researching, testing, and deploying VoltDB.
Given the popularity of postgres, and the relatively low friction solution of (1.), its clear why this could be an adequate solution. Sure you won't be as fast as VoltDB, but as an outside engineer we don't know the potential customers requirements, and if being as fast as VoltDB actually matters.