If youre getting traffic from search engines, then youre going to want to have such a WordPress plugin like this. If you do care about SEO, then you need this. Using iFrames can lower your score by Google and in return lose traffic from search engines.

Hence the reason you need this plugin because now if you create review sites with 3 or 4 affiliate miner links (iFrames) per page, then it would be a good idea to turn off affiliate miner when you get a visit from search engines.