I dont use it myself, so some others can vouch for me here. The biggest reason to use PiKVM is to access your computer “physically”. Internet down on server? KVM. Change settings in BIOS/UEFI? KVM.

I would also take a guess that you have misunderstood the requirements of VNC. The documentation states that you dont need VNC at all to make it function, but its an alternative to the web interface