This cartoon, drawn by a teenager, is a reminder--for me at least--that while just about every high school kid is on the web today, their choices of platforms sharply define their identities.
I get the impression that marketers believe that 100% of the 12-17 set are on facebook and twitter. Even if that were true (it's definitely not, especially when it comes to twitter), teens aren't there uniformly. They may also be trying out different personality styles, using different venues to express themselves differently.
Brands that focus all of their attention on these two platforms could risk missing the edgiest, most creative and nerdiest groups (all of whom are likely to overindex as future tastemakers).
Moreover, while brands might believe they are on the cutting edge simply by participating on both facebook/twitter, they may actually be relegating themselves to "vanilla" status.
Cartoon credit: [Taylor-Ruth / Hanging Rock Comics]*
* The age of the cartoon will ultimately be significant to the message: the drawing was originally published in July 2011, just after the invite-onlylaunch of Google+ and the $30M myspace fire sale.