Encyclopedias, dictionaries, and other types of reference materials often conform to a rigid and pedantically defined aesthetic. This aesthetic is more about context, appearance, intuition. Editing is an art form.

Conveying meaning differs from conveying the intended meaning with clarity. When you have to say 'most people', we already have a problem. Reference material should refer. Leaving it up to intellectual interpretation is simply no good for material that is meant to record and preserve information.

That said, this possibly has nothing to do with the difference between 'comprised of' and 'composed of'.