What happens when your nuclear reactor supplier goes out of business? What happens to your handle when your razor blade supplier goes out of business?
When an IoT maker adds 'cloud' to their product and makes it inextricably tied to the product's functionality, you have to be able to rely on their ability and willingness to maintain the cloud services for as long as you use the product.
The problem is that a cloud-controlled garage door opener creates an unnecessary dependency on the continued existence - and good behaviour - of the vendor, unless one thinks that being able to open it from anywhere in the world is an essential feature of a garage door opener.
Even if I just wanted to control the door from my desk at home, I'd still benefit from it being IoT-based.
This is an utterly stupid comparison. Razorblades cost less than 10 cents and are disposable by design. You don't spend $100 on a garage door monitor, or $1000+ on an appliance or TV expecting to use it once and throw it away.