Comment by jandrewrogers

It tends to break composability.

The behavior of the library logging can be incompatible with the architectural requirements of the application in dimensions that are independent of the library functionality. It requires the user to understand the details of the library's logging implementation. Even if documented, design choices for the logging will automatically disqualify the library for some applications and use cases.

Is writing the log a blocking call? Does it allocate? Synchronous or async? What is the impact on tail latencies? How does it interact with concurrency? Etc.