Yes, WP can be used as a CMS - I've done it several times.
why would someone create a website using WP instead of Dreamweaver?
That's like asking why someone would make an omelet with eggs instead of milk. Dreamweaver is a program that writes HTML and creates static pages. WP is a program that creates dynamic pages on the fly. You can use Dreamweaver (if you so choose) to create your site templates, but it can't make a blog for you. You don't upload Dreamweaver to the server and use it as a blogging tool - it's used to write code and nothing more. WordPress *can* write code, if you so desire to use it for that, but that's not it's main function.
You don't have to use WordPress as a blog - it's very effective as a CMS. There's stuff in the codex which can tell you how to accomplish what you want. Don't read it and think "this is info only for bloggers" because *all* of the info can be used and implemented to make your site a CMS "static page" looking site without a blog. Look at template heirarchy to get ideas on how to separate each section of the site. The Loop will tell you how to reduce posts to only 1 posts per page, so each section is a "blog" but with only 1 post showing (thus implementing the CMS system - it looks static, but it's not). I've used the loop to show excerpts of 4 different categories on the front page, so the home page gets updated with new news - if only one category is changed, that's the only exceprt that changes on the front page.
There's all kinds of things you can do - it just depends on what you're looking for. The codex certainly has all the answers you need - just don't read it like it's for "bloggers only". :)