Author here. This decision was more about ease of implementation than anything else. Our internal application logs were already being scooped up by GCP because we run our services in GKE, and we already had a GCP->Datadog log syncer [1] for some other GCP infra logs, so re-using the GCP-based pipeline was the easiest way to handle our application logs once we removed the Datadog agent.

In the future, we'll probably switch these logs to also go through our collector, and it shouldn't be super hard (because we already implemented a golang OTel log handler for the external case), but we just haven't gotten around to it yet.

[1] https://docs.datadoghq.com/integrations/google_cloud_platfor...

Their collector is used to send infrastructure logs to GCP (instead of Datadog).

My guess is this is to save on costs. GCP logging is probably cheaper than Datadog, and infrastructure logs may not be needed as frequently as application logs.