Search engines only revisit websites that publish new content. Blogging gives them a reason to come back regularly, which keeps your site indexed and discoverable in search results.
a search engine will come to your website. They'll go through every page and they'll index what they want and they won't index what they don't want. It's only the important stuff and the search engine is who decides what's important and what isn't that gets indexed. Search engines are looking for new content. If you're not offering anything new, why on earth do they need to even come to your website? This is what blogging does. It keeps them coming back looking for the new content.
