Why do we need vsync and hysnc in the LCD driver?

Question

I have doubts about the android / linux framebuffer part, so we need hysnc, vysnc. Because, as I remember correctly, these terms are used in the case of CRT. But, despite the fact that we use the LCD, why do we need it, we can use a simple signal to indicate that the row / column is complete, so we need to wait a while to indicate hsync and vsync (the time I have in type of HBP, HFP, VBP, VFP). Please clear my doubts about this.