I just connected my garage door opener to Home Assistant by taking apart the remote and wiring the button to a Zigbee relay. They can't stop me, no part of this is connected to their cloud. In any case, smart home stuff should never rely on the cloud.
"unauthorized users". They are authorized if they are trying to control their own garage door.
The company I work for has a policy where we don't block third party clients, as long as they use a uniquely identifiable user agent and API key that we provide to them. That way we can easily monitor if they're calling endpoints excessively and make sure that our alarms don't go off when they did something wrong, but still offer power users flexibility. Power users are the users you can get good feedback from, and they spread the word more than a regular user would. If keeping them happy doesn't require active effort, it would be silly to start a cat-and-mouse game just to keep them busy and angry with you.