Dude, people with big arms are telling you that they ARE much use as a stand alone exercise. Yes, they DO build strength. I was curling 90lbs dumbbells before I quit doing alternate dumbbell curls and that is after starting with only 35lbs dumbbells my first time in a serious gym. Are you saying I didn't add strength or that it wasn't much use?
Your biceps are not just "beach muscles". If you plan on benching over 400lbs you had better have strong biceps because they aid in stabilizing the weight.
You all have been brain washed by this bullshit by trainers acting like biceps can be half assed and you can still make progress.
Quit listening to little people who try to tell you how to get big.