When you want to achieve some project milestones, you definitely have some contraints to work with, and when you are working with a team you often hold meetings to brainstorm about these ideas, however I am pretty sure many of us do the mistake of putting the constraints in front of them right at the beginning of the first discussion. This might turn out to be ineffective since most people get biased by constraints.

It makes more sense to convey them the idea without constraints, let them prepare some document about their thought process and then introduce the constraints in the next meeting.