Because in a living language, people pronounce things fast and naturally. It’s a sign you are alive. In a dead language, such as Latin or Sumerian, everything is pronounced correctly all the time since the forces that affect living languages no longer are at work.
If the Germans won the war, their scholars studying Judaica (who were building up a massive library by pilgering sefarim all over Europe) would have pronounced everything exactly and correctly, unaffected by any living people who really cared about the materials.