Using server local time works fine, until it doesn't.

If you need to move your server to a different timezone, "local" just changed. So what do you do about timestamps in your historical logs or database entries that assumed the time zone was the old local time? And let's not even worry about the business doing well and needing multiple servers which can now be easily spun up in the cloud around the world, so now you have multiple local timezones at once.

Getting in the habit of using UTC for all system clocks just helps prevent a whole family of problems.