It is one of default settings in network equipment. Usually, the OEM set this to UTC+0, or the region of manufacturing.
If it is not set correctly per specific site condition, then system events, alerts would be out of synchronization. Even the best SIEM solution fails to correlate the sequence of events for problem shooting, digital forensic.
Best practice is to review component configuration and assign correct parameter values, have these validated in Site Acceptance Test before commissioning. It is human issue regarding proper design and deployment of tools.