I've never claimed to be flawless. It's a bad practice, but there are times when everyone gets tired of endless explaining and will just make the questions go away so that everyone can get back to doing what needs to be done.
Legitimate ideas never generate this response. Typically, it is when the other individual is trying to either a) whine to make their pet view (that I/we've already evaluated and dismissed) be addressed again b) is talking to hear themselves talk (we all work with those kinds), or c) is trying to generate huge masses of work for others with little, no, or negative gain to the organization. The nice thing is, if they can still support their view when given the firehose of info on why a current design or action plan is what it is, then they probably have a good idea that needs more evaluation and the rest of us have missed something. But yes, at its core, it is more of an argument tactic than it is an education or discussion tactic (with heavy roots in arrogance and is used when the interest is no longer in discussing, but making the other party go away).