This is a good example, why not all devices should be connected to foreign servers. Errors can happen everywhere. But it could end badly, if some Corporations make errors and creating trouble, which would otherwise not happen.
In the case of the 3D-printer it is not that bad (except it destroys itself or even gets on fire), also you can turn it off. But imagine a smart stove top that lights up a towel (or something similar) while nobody is home.
Not, that I think that it is not useful to have something like that, but wouldn’t it be nice, if that stuff would work locally? (with the WireGuard integration in modems, the access from outside of home with the smartphone, should also be no problem for non-tech people)
There’s benefits to having your 3D printer connected to the internet though. It allows you to monitor the progress and lets you cancel the print if there’s an error, potentially saving uou a lot on filament and repairs.
That being said, having them connect to centralized servers is dumb. Just add a Raspberry Pi with octoprint flashed onto it and set up your own connection if you want that feature.
You can also just VPN in. It’s not hard, and many routers have that ability today.