Meh, it happens quite often that when you are brainstorming you have more than one idea you want to share for others to evaluate. It happens to me quite often in real life that I have my preferred option, then I also comment than an alternative would be possible... then the rest are convinced about the alternative.

This is different than lazy users posting new solutions instead of editing their current ones to improve them, yes. Then again this is not much of a big problem since Brainstorm allows you to select more than one solution.

It only becomes a hassle when you have more than a dozen of solutions already and then a new one comes adding just too little. But not even that is a real hassle in focused brainstorms with only a few solutions listed.