Only good reason would be for bulk log searching, but a lot of cloud providers will already capture and aggregate and let you query logs, or there are good third party services that do this.

Pretty handy to search a debug_request_id or something and be able to see every log across all services related to a request.

> but a lot of cloud providers will already capture and aggregate and let you query logs

This is just the cloud provider taking the dependency on their logging service for you. It doesn’t change the shape of the graph.

Logs need to go somewhere to be collected, viewed, etc. You might outsource that, but if you don't it's a service of it's own (probably actually a collection of microservices, ingestion, a web server to view them, etc)

In my experience this is best done as an out of band flow in the background eg one of the zillion services that collect and aggregate logs.