But would mean something different. Also it doesn't make sense to call those people Austrian. The point of the phrase "present day Austria" is to describe the g

But would mean something different. Also it doesn't make sense to call those people Austrian. The point of the phrase "present day Austria" is to describe the geographical area which is now Austria, while recognizing Austria did not exist (or was something else) at the time. Just as an example, Mozart was born in present-day Austria, but he was not born in Austria, since Salzburg were not part of Austria at the time.