Org mode is slightly older than Markdown, and certainly older than Markdown's status as a default way to mark up text.
More than that, it doesn't make sense to think that Markdown is the best solution, or at least the best solution for all use cases. People should continue to try and innovate, at least if they're aiming for something bigger than trivial improvements on the status quo.
More than that, it doesn't make sense to think that Markdown is the best solution, or at least the best solution for all use cases. People should continue to try and innovate, at least if they're aiming for something bigger than trivial improvements on the status quo.