Professional firms that produce contracts and reports generally have document format guidelines and standard templates. They may also have approved typefaces, up to and including brand-custom typefaces. And while these things could be applied by document editors or tools later based on a simple set of text documents (I'd be in favor of that), in reality everyone works in Word, and the working Word documents are what will eventually become signed legal documents or stamped and sealed engineering studies, or similar. Styling does matter.
Ideally, yes. But so many people only know of Word, or have been writing using Word for so long that they won't change their workflow and they simply do what works for them.