When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.
Search engines are smart, but they still need help. The major engines are always working to improve their technology to crawl the web more deeply and return better results to users. However, there is a limit to how search engines can operate. Whereas the right SEO can net you thousands of visitors and increased attention, the wrong moves can hide or bury your site deep in the search results where visibility is minimal.
It is increasingly advantageous for companies to use social media platforms to connect with their customers and create these dialogues and discussions. The potential reach of social media is indicated by the fact that in 2015, each month the Facebook app had more than 126 million average unique users and YouTube had over 97 million average unique users.
If you decide to go into affiliate marketing, understand that you will need a lot of very targeted traffic if you want to make any real money. Those affiliate offers also need to provide a high commission amount to you on each sale. You also need to ensure that the returns or chargebacks for those products or services are low. The last thing you want to do is to sell a product or service that provides very little value and gets returned often.
If you’re Matt Cutts and a billion people link to you because you’re the Spam guy at Google, writing great content is enough. For the rest of us in hypercompetitive markets, good content alone is not enough. There was nothing wrong with sculpting page rank to pages on your site that make you money as a means of boosting traffic to those pages. It’s not manipulating Google, there’s more than enough of that going on in the first page of results for most competitive keywords. Geez Matt, give the little guy a break!
While ordinary users were not that interested in pages' scores, SEOs of a different caliber felt that this was a great opportunity to make a difference for their customers. This obsession of SEOs with PageRank made everyone feel that this ranking signal is more or less the only important one. In spite of the fact that pages with a lower PR score can beat those with a higher score! What did we receive then, as a result?