If PE is so important why is LinkedIn http://www.google.com/finance?q=NYSE%3ALNKD http://www.google.com/finance?q=NYSE%3ALNKD not getting bashed as fb is. Both

If PE is so important why is LinkedIn http://www.google.com/finance?q=NYSE%3ALNKD http://www.google.com/finance?q=NYSE%3ALNKD not getting bashed as fb is. Both are kind of social networks (used differently with different target audience) . LinkedIn is trading at 600+ PE.