Someone could have acquired credentials (phishing, social engineering) and could gain access now that they also have a server name.
Or someone in the same company could have access that they're unaware they have, and since they know the server name they try accessing it. I've certainly done that myself (I'm a curious person ) but I didn't have official authorization to access those servers.
You may have heard of the principle of least privilege, the idea is to grant only the absolute minimum permissions to do a particular job. This ensures against accidental (and sometimes deliberate) changes to a system. Part of that principle is to limit dissemination of information that could be used in the same way.
Do some research on "data breach", "cloud service breach", etc. Lots of stories about people posting server names somewhere in the cloud and they get scooped up by bots.