A blog is just a type of website. It can help a website if you put good stuff on the blog pages, as with any static webpage.
>> On my travels I have seen some sportsbooks have hundreds if identical blogs on blogspot, all pointing at each other over and over.
Some have the sportsbook above the content. Some just a banner and bundles of links to the sportsbook.
I can’t see Google smiling upon it’s usage of bandwidth for such seo techniques for long. Blogger.com has implemented procedures to stop the auto opening of multiple blogs anyhow.