Containers with their 940px width are a convenience, a standard for some, a good practice for others, kind of an ideal grid setting for me, for the time being. They're all that but not an obligation. You're free to design as you like and use divs as custom containers.
Wether or not you need to put sections to host your containers depends on your understanding of HTML5 tags and when they should be used. For example, about the section tag: http://www.impressivewebs.com/html5-section/
Doing more researches about HTML5 elements, you'll find that interpretation and advices vary. Webflow made choices, pushing you to use containers into sections to produce, I guess, what they think is the best HTML5 compliant code.
But for your structure you can build everything with divs and set the tags appropriately in the settings panel in Webflow.