Usefulness of an MQ layer in an ELK stack
An ELK stack is composed of Elasticsearch, Logstash, and Kibana; these 3 components are owned by the elastic.co company and are particulary useful to handle Data. (ship, enrich, index and search your Data)
In computer science, The message queue paradigm is a sibling of the publisher/subscriber pattern.
You can imagine an MQ componant works like several mailboxes; meaning that publisher(s)/subscriber(s) do not interact with the message at the same time, many publishers can post a message for one subsriber and vice versa.
➡ Redis or Kafka or RabbitMQ can be used as buffer in the ELK stack.