I was about to comment that while any database can serve as a log replay and may even be feasible for these volumes, scaling it at high volume later would be extremely hard - I have experience with this in a multi-petabyte set up and its a nightmare using an RDBMS.

But, the article says "In Apache Kafka, the Monolog is implemented as a single-partition topic" - losing all the goodness Kafka provides around scaling. This setup now is no better than an RDBMS with master/slave replication.