I agree with the sentiment, although not sure if "error" is the right category/verbiage for actionable logs.

In an ideal world things like logs and alarms (alerting product support staff) should certainly cleanly separate things that are just informative, useful for the developer, and things that require some human intervention.

If you don't do this then it's like "the boy that cried wolf", and people will learn to ignore errors and alarms since you've trained them to understand that usually no action is needed. It's also useful to be able to grep though log files and distinguish failures of different categories, not just grep for specific failures.