I see a number of questions (https://robotics.stackexchange.com/questions/10313/design-of-scara-joint-problem) where a combination of english as a second language and a question from a user new to the stackexchange world (https://robotics.stackexchange.com/users/14287/alaa-momen) causes the question to be put on hold rather quickly.
Some of these people might have contributed to robotics.stackexchange in the future had they not been turned away so quickly.
Robotics straddles a lot of disciplines. It can be difficult to articulate a question well when you are asking about an area you are weak in, more so in a second language.
Does it really hurt the site if you leave the vague questions open for a couple weeks; give them a chance to be clarified? Give the new community members a chance to participate and learn?
For the question above, the user does not have the experience to know that the kickstarter project they saw was clearly created by amateurs and might not be a good one use as an example; but on the other hand it's clear that they are looking for a low cost joint design that would work for hobby type maker machines with SCARA kinematics. As far as questions about mechanism design go, that's not too bad for someone that's not a mechanical engineer. A small amount of shepherding could turn this into an interesting question and hopefully a couple good answers.
This question is just one example of the broader issue though.
What happens if you aren't so quick to put questions on hold?
Here's a vague question that could have been closed as too broad, but in the end was nicely illustrated. Preventing leaks in motor shafts for underwater bots
Here's a shopping questions that should have been closed but apparently is one of the best robotics.stackexchange has to offer given the upvotes and views. How to choose the right propeller/motor combination for a quadcopter?
My main point is that I think that putting questions on hold as quickly as you do hurts the growth of the site. Sometimes the only way to clarify a question in a topic as broad as robotics is to propose an answer and then refine both the question and answers iteratively.