Why Is Number Lock With Verizon Important?

Verizon does have a sim protection in place called Number Lock, and they've had this free service since 2020 before any of the other carriers had anything in place. You simply activate the Number Lock protection on your Verizon app, and your number can no longer be transferred to another carrier, sim, or device until you personally remove the lock. Why is it so important for you to put in Number Lock with Verizon or the equivalent sim protection with AT&T or T-Mobile? Or if you're with an off-brand, do whatever their procedure is.