Title text:
It's important for devices to have internet connectivity so the manufacturer can patch remote exploits.
Transcript:
[A store salesman, Hairy, is showing Cueball a dehumidifier, with a "SALE" label on it. Several other unidentified devices, possibly other dehumidifier models, are shown in the store as well.]
Salesman: This dehumidifier model features built-in WiFi for remote updates.
Cueball: Great! That will be really useful if they discover a new kind of water.
Source: https://xkcd.com/3109/
To steel-man the argument some more, if you have variable-rate electricity, it could turn on when electricity is cheap.
This can be done with something like Zigbee. Or even simpler: you hook a non-connected device up to a "smart" power socket. No need for the device itself to talk to the outside world.
You still have to have some device connected to the internet. This just transfers the problem from the humidifier to the outlet.
I run home automation with lights, switches, outlets, heaters and some more and not a single device has internet access. They all use Zigbee (a simple radio protocol) to talk to homeassistant which is open source and hosted on a machine that lives under my desk.
Separating tasks between the dehumidifier and outlet has the advantage that each individual device can be a lot simpler, leaving less attack surface. My power outlet can't read the humidity sensor, it doesn't need to talk to an external server, it doesn't even need to know that the thing connected to it is a dehumidifier. It's just a chip that receives a radio signal and toggles a relay on or off. That's it.
Separating the two concerns also lets me replace the devices separately if one breaks or my requirements change. If I suddenly need wifi or bluetooth instead of Zigbee or if it's for some reason no longer supported by homeassistant, I can just replace a 9€ outlet instead of the whole dehumidifier that could get bricked by the proprietary app losing support.
Home automation is still a dark art as far as the common person is concerned. Full of fear mongering from the media.
Much like 3D printing was very mystical and full of "oh no 3d printed guns!" We have gone full appliance with 3d printing and it's no longer gatekeeped by geeks in their basements.
I'm glad I still have at least one hobby that hasn't gone mainstream and I can still geek out on ESPHome.