No one will read your comment if it's long, and if you aren't fast enough, someone else will have replied and then no one will see your comment.
That's another problem I see with Reddit. There's an extra meta-game you have to play if you want yourself heard, that really shouldn't exist. Discussion should be just that: discussion. Not a bunch of flaming hoops you have to jump through, at just the right time, in just the right way.