Yeah I can see how that would be confusing. That’s what we’ve began calling "divitus" where people just put way too many useless divs into the markup. In that image, I see no real use for the colmask, colwrap, or col1wrap. Sometimes there is a reason to wrap a div inside another div, but they present no compelling reason for it there.
It’s extra confusing how they call the div on the left "right" and the div on the right "left". That’s the sting of using descriptive text like that for class names, it comes to bite you. Much better to call it "main-content" and "sidebar", so whether that sidebar is on the left or right, it’s name still makes sense.