blogging means content (walls of text), and the googlebot consumes text to grow big and strong. So, the more content you feed it the bigger and happier it gets with your site, so it will rank it higher (or it used to rank it higher, not sure that his still the case).
Blogging is important and somewhat needed, albeit not on its own anymore as - apparently - google doesn't like pure blogs anymore because they steal delicious traffic and rankings from the mouth of the big budgeted sharks and vultures that feed on everyone else...
But yeah, blogging can help you get better rankings, more traffic and more sales, both directly and indirectly...