It seems odd to devote a long and detailed article to the rollback-journal mode, which is older and is rarely the one you’d want to use. The write-ahead log has better performance and much better concurrency, allowing simultaneous reads during a write.
SQLite’s docs explain the pros and cons, but basically you’d only prefer the rollback journal if your OS doesn’t support shared memory, or your database is on a networked filesystem (which is itself often a terrible idea.)
perhaps you missed the final section? this is first in the series, the next is about WAL mode. Also, journal mode is the default so it might be useful to understand how it works in order to understand why you (often but perhaps not always) want WAL mode instead.