<i>&quot;I think you&#x27;re underestimating the importance of Facebook information towards making viable free content. The basic, accurate information you receive from the FB SDK really helps salespeople identify qualified leads for trial-to-paid conversions; the info also can be used to tell you what other websites people visit or software they use.&quot;</i><p>I generally consider this kind of information warehousing and sharing unethical. While I understand the business case for it, and I understand that facebook has permission from their users because of the ToS agreement, I don&#x27;t want to inflict it on my customers (who are often Open Source and Free software nerds who take their security somewhat seriously). I am a facebook user, but I don&#x27;t like what facebook does to privacy. Google, same story.<p>So, I view participating in those login systems as low-grade evil, as it contributes to the incredible stockpile of data facebook and Google have about all of us. I don&#x27;t make a big deal about it, and I use sites that require it, but I don&#x27;t have to like it. And, if there were a way for me to provide a similarly nice user experience to my customers without invading their privacy in any way, I would do so.