Some of these sites have simply mastered the promotion that is required to sustain an ad-driven social media platform or blog. I think you have to also recognize that sex sells. People click Like or Subscribe to these sites because they are promoting sex, sexy bodies, etc. over quality content.
With that being said, I think consistency matters too. A lot of these sites produce lots of content on a consistent basis, no matter how trivial. This can be done a lot easier for gossip and pop culture blogs because they are tons of gutter-level shit out there. I think finding the right target market and producing consistent and high-quality content is a much better driver towards success. I had a friend who created the Well Fellow Blog which is a health and lifestyle blog for gay men but it is gear towards the white men so I don't come back to the site as much because the content is not written for me and my tribe.