This is a great example of survivor bias. Just because you can list a handful of high-profile successes by no means discounts the arguments against Pinterest.
I can give you an equally invalid example of failure bias:
Groupon,
Friendster,
Myspace,
Digg,
Zynga,
etc
I can give you an equally invalid example of failure bias: Groupon, Friendster, Myspace, Digg, Zynga, etc