Do not argument about it. It works! Your navigation should not lead spiders away from your website so prevent them from following navigation that does that. The way to do that is to include the term rel = "nofollow" within the html tag for the navigation link. Do not put all of your navigation links on every page, unless you block them to spiders. Do not allow spiders to follow affiliate links or you will lose your keyword relevance.
You can lead the spiders along the path that you want them to by judicial use of navigation links, and if this is a logical path that allows all of your web site to be navigated without confusing the navigators, you have a great chance of having several of your pages listed high for the search term, or keyword, that each page is providing information on.
That word 'information' is the all important one. Do not forget what a web site is for. It is not to please search engine crawlers, but to provide useful information to the search engine customers. If you do that honestly, and write honestly about the topic, the search engines will be kind to you. If you try to cheat by overuse of keywords, but with little content, then you will be found out.
Finally there are the back links to your web pages. You need links back from other web sites for Google to believe that your site is of value. Not only to your home page, but to each individual, page, since Google lists each page separately.
One way leads to success, the other to failure. Be a winner and use these search engine optimization tips to your advantage, but also provide useful information to those that the search engines send to your site. If you fail to do so, the search engines will soon stop sending anyone to any of your web pages. SEO can do so much, but most of it is up to you.