I thought about this a lot, and my node How to know whether question in SOPW is entirely answered or not? is a start of my thought, and long after people independent of me thought about that as well, and node that confirms this is Has anyone answered this SOPW?

This really seems to me like good thing to fight a problem when some low quality questions, or questions of not full coverage arrived, and many wise people after that will not even read a question because it has many answers.

Let's give a person who asked a question right to "reject", hide or even delete an answer that he thinks does nothing good to add!

Simple questions gets simple answers really quick, and it's not bad considering many people get their answers quickly, and all is good.

But it's much worse when complicated question receives a couple of stupid replies, and then became unnoticed after that.

Simple downvoting does not seems enough to me, because this just do not reflect a situation: many people up/down vote a node just for grammatical rules, for example, or for something not reflecting a situation.