A supermarket may have 30 freezers. You don't want them to beep loudly if someone forgot to close the door. Instead you connect them to a central monitor. A local employee can see on the monitor which freezer has a problem and go see the issue.
The monitoring is as well a proof that the cold chain was kept.
This network was local to the market. Then one day it was found better to collect these data to a modern dashboard, and so the local network ends on corporate network.
Why not? It works as an alarm, is simple in design and requires no external input.
They need to be checked 3x per day anyway for temperature so someone will notice eventually. And checking temperature must be product core temp so no remote monitoring. Unless haccp changed massively over the last 20 years to "we don't care anymore".
With centralized monitoring, this all becomes much easier, and you can inspect a whole row of freezers in less than a minute. You can even do it remotely, just watching when customers open and close the doors on a security camera and checking that the control system registered it correctly.
See also: dump trucks that have alarms if you start to move while the bed is up. It's a great safety feature on the highway, but it's annoying on the job site if you can't just dump everything out while standing still, so it frequently gets disabled by the workers, especially if it starts to misfire. This is how you end up with dump trucks going highway speeds with their beds up taking out overhead signage and slamming into bridges. The stakes are much higher, yet workers would still rather rip out the alarm.