Limited amount of characters (letters) in a post

I was trying to post a very detailed post, and I ran into a character limit. It seems to be somewhere around 4100 characters.

While I realize that's a lot of character, with good formatting and urls, it actually becomes significantly smaller. (And I'm used to the old Forums and Reddit, where there doesn't really seem to be a character limit.)

Is there a reason you're keeping the number small? Or is it just while you're in beta?