Why components involved in request response flow should not consume messages on a kafka topic?

As part of design decision, the components(microservice) involved in http request-response flow are allowed to produce messsages on a kafka topic, but not allowed to consume messages from kafka topic.

Such components(microservice) can read & write database, talk to other components, produce messages on a topic, but cannot consume messages from a kafka topic.

What are the design flaws, if such components consume kafka topics?