To answer your question, the problem with the current system is that people are assuming that if the challenge to a motion doesn't come immediately, it passes. That means any two people can pass an arbitrary motion to change at any time just by posting in rapid succession. This is a huge problem. Imagine if you made a bill that was to create a new government agency and some people randomly added "and we're declaring war on Lor" in into the bill through an eleventh hour motion to change at 3am and you weren't there to challenge it.