Why should I simply not press "Enter" multiple times to get my content on new page while using MS Word?

If you use "Enter" multiple times to get the content on a new page, there will be a problem when you update the content. Suppose you started chapter 2 on a new page. Later you wanted to add few sentences to chapter 1. Now, as you add that content, the first line of chapter 2 will start going down and will no longer start from the top of the new page. Similarly, if you delete content from chapter 1, chapter two will come on the previous page no longer starting from a new page. This is because MS word only knows that there were so many "Enter"s between chapter 1 and 2. It has no idea that you wanted chapter 2 to start on a new page. This will be an ongoing formatting headache.

So, the right way to start something on a new page is to use page break feature of MS Word. When you use page break MS Word knows that you want the content on a new page and irrespective of how content changes, it will intelligently always start it on a new page.