The more interesting question is why should you value the opinion of a panel more than an individual? Is the writer not entitled to an opinion on the best board game of 2017 just because a group chose something else?
Also, one should consider group dynamics. Who's to say if everyone on that panel valued the game that won equally? Perhaps they all had their personal favourites, but chose a different game as it was the least contentious. All you can really say about a decision made by a panel is that it was the best decision they could make on aggregate, not that it was a true reflection of individual preferences.
All that aside, "best game of 2017" is really just "best game I played in 2017". I honestly don't know when we're collectively going to grow past handling subjective comments in an objective way, but I hope its soon.