If your sister can ignore the comments and ratings just fine, I'm optimistic of her ability to ignore ads and social integration as well.
And if at some point she does sees a Tickle-me-Elmo ad that makes her go nag her parents to buy her a Tickle-me-Elmo doll is that the end of the world?
It's always astounded me that in America (I am just assuming that the blog author is American) you have people who feel that non-essential services (like internet video distribution or email) should be ubiquitously free and available but at the same time you have people that feel health-care for everyone should not be a basic human right.