The outrage is there because people care. And they don't care about $50 that some parent spent somewhere for her kid - because that's non-news. Really.
And if people care about something that much, you can imagine the social implications of not being good enough in it.
Now, people care about this issue a lot because being a good in a game is a certain status that is being challenged by the factor of having a supportive enough parent that not everyone has. Cue the "I'm a gamer but..." and "My parents would never..." responses on Twitter cited in the article.
Conclusion? $50 well-spent. For the cost of a dine-out for two, the kid gets skills that impact his social life in a positive way.
Good one on the parent.