Why Have I Never Seen a Content Locker?

I am interested in SEO, but I still am skeptic of the lucrative nature of it. Why is it that I have never encountered a site protected with a content locker (survey-based) myself if it is one of the best methods of CPA available for content?

I mean, sure, there seems to be lots of people out there willing to purchase BLOG or other such articles on the cheap for this purpose. But with all that you have to invest in SEO, it doesn't seem like returns are that great if you aren't following a successful formula down to a 'T'.

Any thoughts? Please provide some sites protected with survey-based content lockers.

because you won't find content locker on porn sites ))
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try to download a file from sh?recash, with a instead of ?
or other option go on google,com/ncr and search for "dota 2 key" and try the first site

http://shar3c@sh/download.php?file=1925667

quick google search mate

I don't use content lockers, and I convert just fine. SEO is all about the keywords.
Most don't have the homepage locked, but rather an inside page that you probably never navigated to.