I have several blogs, each with a different focus. And yes, some have landing pages, tho NOT at the root domain. I name my landing pages to reflect what they are, and drive traffic to them using ethical techniques, not bait and switch.
On my blog (for example), I talk about a free report I am giving away. THAT links to a landing page which asks for their name and email address. I also have links planted around the web that point to it, with anchor text that reflects what is at the other end of the link.
My blog brings me in traffic, visitors and later, folks who come to know, like and trust me because I deliver value. My landing pages aren't the focus of my site, just one more method to connect.