Power issues can cause problems that the hardware glitches into states it should not be. Changing something in the BIOS or updating it. Hardware defects. OS upgrade fails (Kernel bug causes the network driver to fail) Etc. Etc.

Those devices are not for the weekly “oh my setup failed” its for the once in 10 years “i am on vacation and the server is not reachable and for some reasons my system crashed and has not rebooted by its own”

And for below 100€ it’s a no-brainer.