[realityfactchex]

Ribbon vs. classic toolbars is the comparison to be made. (Sorry for saying menubar when I meant toolbar up above; that was probably confusing.)

I'll try to explain the gist of it, since that seems to be the question:

As you say, one facet of ribbons is they are essentially tabs. So, ribbons obscure whatever is on "those other tabs". Often, with additional annoyance of taking more space than needed to show what they do show (which often is not want is needed). And any section within a given tab can have its own peculiar (varied) layouts. (Continuing the "find it in the hierarchy - customized for the purpose to make your life easier the way a designer thought would help!" paradigm.)

Contrast with toolbars. Show the ones you need, customize them if wanted. Icons and locations are quite effective for selecting actions. They can all be seen at once. They do what they say. No constantly interpreting the interface flow to find stuff.