My personal opinion on this:
There is maybe potential for increasing knowledge of Word formatting and it's tools. My experience is more like if a Word user want to spend some time he will find out it's worth to dive a bit deeper in this subject.
Anyway, as long as a user is ok with a result he should do it in the way he feels comfortable to do it.
Edit: Yes, a Word user should learn to work with styles as this is a general concept for a Word document. Word is not a type writer as some users always seems think about.