If you're talking about articles that naturally group into categories, then the developer is right - categories and posts would be easier to manage. Pages can be assigned as sub-pages of another page, but that's not really the same thing, and the whole navigation thing gets a little trickier when you start putting a whole bunch of content out there on sub-pages.
My company uses Wordpress as a CMS for our corporate site. On our website, we use pages for things like our resource download page, our "about us" page and the contact page -- things that are relatively static and that essentially stand alone or have only one or two equally static sub-pages. And we use the category/post format for our press releases and our newsletter articles (among other things). Stuff that gets added to more often, and that has sometimes dozens of related articles.
With custom menus and a judicious use of widgets, you can get really creative with how you display and navigate among these articles.
Maybe if I understood what your concerns were with posts and why you're leading toward using pages, I could better address the issues.