You can use Lucene and implement these types of features on top of it if they're important to you. I think what the author was trying to say was the Lucene cont

You can use Lucene and implement these types of features on top of it if they're important to you. I think what the author was trying to say was the Lucene contributors decided to focus on a certain thing and leave other implementation features up to people using the library. Lucene gives you a lot of levers to control how it works and if you want to build a distributed, MVCC, ACID compliant datastore on top of it, you can. It's just not a concern of the library.