Originally Posted by 79pmooney

That stem bolt doesn't have to be socked down tight. All it needs to do is make it so a little effort is required to twist the handlebars. All the tough twisting jobs a stem ever sees happen while you are not riding. (Knock your steering that hard riding and I promise you, you've got bigger issues than the stem twisting.)

If you really had your stem bolt too loose, it could slide down on a hard bump but it isn't going anywhere. This isn't like the bolt(s) at the handlebar clamp where failure can have really bad consequences. Should this happen, you just ride home with your bars a little (or maybe a lot!) lower, get out the wrench, raise them and tighten slightly tighter. No big deal.