A well-beaten child might obey best, but obedience isn't the only goal of discipline - nor agreement the only goal of argumentation.

You've got the wrong kind of fear there-- the effective use of fear is to make your listener afraid of some third party or event, not to make them afraid of you.

If you make people afraid of you, they might give in, especially if you have physical power over them. You might get useful compliance that way. However, you're also likely to get people to avoid you if they can, or to push back compulsively.