There is nothing keeping more people from learning it, though; as soon as a few people have learned it, the knowledge about a language can be proliferated to o

There is nothing keeping more people from learning it, though; as soon as a few people have learned it, the knowledge about a language can be proliferated to others. It's just that we generally don't care a lot (beyond employing a few thousand(?) people world-wide per language) for ancient texts.