Well typically the outlet convenes with a bunch of people who have played a wide variety of games, so I feel they have a pretty good pool of minds to pull from.
Also I don’t think it’s a bad system compared to having it be all user voted. Golden joysticks already exist for 100% public vote, and that can be easily influenced by bots and the like. Also half of the games nominated for game of the year this year were open world games that were not short. I mean I don’t think many expected in January a crpg would win in a year a Zelda game came out ¯_(ツ)_/¯