OBJECTION!! I know I'm not a mod/admin, but I think I'll add my two cents anyway.
As far as I'm concerned, people don't really learn from their mistakes unless something bad happens because of their mistake. A warning, if anything, is designed as a wake-up call to say "If you keep breaking the rules you're outta here." A little phrase of mine comes to mind: A lesson learned the hard way is a lesson never forgotten. Although you can be too firm sometimes e.g. if the mods warned people simply for mispelling one word in their posts, I don't think the mods here are too firm at all, and are quite nice people once you get to know them a little better.