Shouldn't a question only be put on hold or be closed after a certain amount of downvotes, not a gorup of people deciding to close the question?
The short answer is simply that the way you describe is not currently how the system is set up. A handful of people with a certain amount of standing (reputation), or elected moderators, are given the right to put questions on hold as a way to promote quality content.
A big reason to put questions on hold early is to stop people submitting premature answers. Questions asked without much experience of philosophical argumentation, particularly of the terminology, concepts or logical technologies that have tended to be used in philosophy, sometimes need a little support to help work them into a form that invites strong answers. Otherwise, people might be tempted (and I know I particularly fall prey to this temptation myself) to submit answers to the questions in the form that they've been asked, rather than in response to what it is that the asker might really like to know.
Questions are put on hold whenever it seems like there is some uncertainty as to exactly what the question is asking, so that discussion can take place to help resolve that uncertainty in some way before others try to capitalize on it with cheap and smug answers.