One of the top webpages in the world are search engines. I believe it is so, because high quality search engines save people a lot of time and help them find what they need very quickly. When it comes to your website, it is important that you allow your visitors to use the search option and allow them to browse through your site this way. This is especially important if your site has a lot of posts, since finding them manually would take too much time. Your older posts will eventually not get any hits at all. This is a serious problem, especially for websites that are in a niche where older articles do not necessarily get outdated. For example, a website about pets will have many articles that could be useful for readers for many years, but with no search box, it will be hard to find those articles. By integrating search into your site, you give people more freedom to explore your blog, but you also make your site look more professional. I would say that allowing users to search your blog is a must these days, because you will not be able to compete with other webpages if you will not have this feature.