For the same reason that children go to school in classes based on their age rather than based on their progress. Cost and complexity reduction. These can com

For the same reason that children go to school in classes based on their age rather than based on their progress. Cost and complexity reduction. These can come down in many areas and probably should to give people their own time back to do other things. It's going to change slowly but surely. Already now many of the new generations are used to asynchronous structures it will only increase in the future as new generations appear.