Imagine manually configuring IP addresses for employees. Each device needs a unique IP, the correct subnet mask, the right gateway, and DNS server addresses. One typo causes connectivity issues. One duplicate IP breaks two devices.
Now imagine employees with laptops moving between floors. Each floor has a different subnet. Manual configuration becomes impossible.
DHCP eliminates this administrative burden. Connect a device, get an address. Move to another network, get a new address. No human intervention required.