1 : deserving imitation especially because of excellence : commendable
2 : serving as a warning
3 : serving as an example, instance, or illustration
In most cases EXEMPLARY is used to suggest excellence. Merriam-Websters illuminates us that "usage commentators" warn against using the two terms synonymously, even though excellence naturally warrants imitation. But more importantly: what is a "usage commentator?"
The Columbia Guide to Standard English describes the battle between descriptive linguists and prescriptive (or usage) commentators:
(1) A descriptive approach to language describes in full detail precisely how we use that language. The chief values of this approach are accuracy and an unretouched picture of usage, warts and all.
(2) A prescriptive approach insists that however many variables might be found, there are better and worse choices; it will specify at least which is most appropriate, or likely which is acceptable, or in its most rigorous application, which is correct.
The author further illuminates this point with the EXEMPLARY selection of the word irregardless. Prescriptive commentators would say: Don't use it! Pretend it doesn't exist! Descriptive linguists would then argue: In fact, irregardless does exist, it's in dictionaries, and people do use the word; we'll show you when, why, how, etc.
So, the battle rages on. Merriam-Webster sits in the middle, impartial, sending out emails and reporting back to the lay person like myself.