I Don't Get Vertical Foregrips

My understanding of rifle technique is pretty weak, but it largely breaks down to "whenever possible use your muscles as little as possible." This is because your skeleton doesn't expand or contract, but your muscles are always moving whether you like it or not. Therefore you want to support and aim the gun using rigid skeletal members, not by shoving it about using your muscles which are far more variable. This yields better accuracy.

Enter the vertical foregrip which appears to be designed almost solely to allow you to muscle the gun around. I've tried it and except for being a convenient place to hide a bipod, I find that I'll never get proper skeletal support using one. My accuracy drops into the toilet accordingly.

Now I can understand why some people like it. If I had a select fire weapon, the gun is going to be bouncing around anyway. I'm going to have to apply muscle to it to hold it on target so I might as well affix a convenient lever arm to help me out. But like almost all civilians, I don't have a select-fire weapon. That guy isn't me. Accordingly the vertical foregrip looks to me like something civilian shooters adopted from the military without thinking it through.

Now I'm more than willing to admit my shortcomings in this area. Can someone that shoots a rifle/carbine much more than I do help me out?