"Only experts on "X" can opine on "X" is easily refuted because a non expert can be affected by "X". Another poster used the analogy of eating bad food at a restaurant. One doesn't have to be a world renowned chef to know the food tastes awful. The customer isn't an expert but is still affected by the poorly prepared meal and thus has the right to opine.

As a fan I may not be an "expert" but I still have the right to opine because the team's performance affects my Fandom.