They said that “not interlinking your old blog posts on newer articles is wasting”. Why wasting? Of course, every new article is a chance to introduce your older articles that seems to be forgotten. Interlinking blog articles works just like “related post widget/plugin”.
After some period of time and after optimizing your blog, people are starting to head into it. It is indexed faster. Again, interlinking is very important because it gives opportunity to some readers. It is the same of telling them that “you can try reading the article behind this link”. What are the benefits? Simple. Lower visitors bounce rate, more pageviews, more pages visited by readers and more time spent on your site. The best result, higher blog ranking.