It's mentioned in the comments that the article is geared towards parents of elite players under professional coaches. That comment should probably be placed more prominently in the article, as it changes my opinion on the content. For recreational players, they likely want their parents watching, and their practices are often short enough that it's not practical for the parent to go anywhere. For those training at a high level, they're practicing so much that it's silly for a parent to hang out and watch.