I share your suspicions but I'd go further. The bed industry has always struck me as an obvious scam that plays on people's nebulous health anxieties and also on the tempting cognitive fallacy that, since an 8-hour night is the same amount as an 8-hour workday, the exact physical makeup of your bed is somehow as important as your career or something. It all strikes me as almost completely irrational. People slept for aeons on straw and somehow survived. A bed is a soft flat object, any other abstract properties are just marketing IMO.

So nobody has any agency and we're all just helpless puppets on strings?

A shared account doesn't mean everyone who works there has access to it, or that those who do have access aren't subject to some type of access control.

The article basically goes on to say that the existence of this key makes a huge difference to the security/privacy of the product. It argues that using it, someone could access data from the device, or use it to upload arbitrary code to the device for it to run. However, those are both things the user is already trusting the company with. They have to trust that the company has access controls/policies to prevent individual rogue employees doing the things described. It seems unreasonable to say that an SSH key being on the device demonstrates that those controls aren't in place.

I'm 90% sure it is not a single user. I just don't see how that really affects the security of the product, given that the company that sells it can already do the things the author is saying can be done if you have this key.

To be clear, I wouldn't buy this. I just don't think the SSH key makes it any worse than it already was