You create a few sample infographics and share them on social media so people see what the tool is capable of doing, and between that and the traffic coming from organic search, you start to get a few hundred people using it every month. A few of them like it so much they provide their name and email address so they can continue using it. Now that you have their contact information, you're able to identify some people that would be a good customer fit and keep in touch with them, nurturing them into customers.
Predictably, blog posts are typically written by the bloggers. However, if your team is large enough to have someone dedicated to creating gated assets and premium content -- things like ebooks and tools -- they should also write blog posts to help promote those assets. SEO specialists will also work closely with bloggers, as blog posts are often a company's best opportunity to improve organic search rankings. As such, bloggers should be writing posts that help improve the site's SEO, and drive organic traffic and leads. Their editorial should be informed by keyword research, and optimized for SEO.