cell biology - What is the purpose of requiring two separate binding systems for the antibody response?

I've read that in most cases, B-cell activation requires helper T-cells. This requires antigen binding by both antibodies and T-cell receptors, using two different antigen-binding proteins, recognizing two different epitopes.

Why is this so complex? Would the overall antibody system still work if B-cells required only antibody/B-cell receptor binding?