> I don't think this definition is very helpful though.

Because it’s a straw man, and straw men aren’t helpful for discussion. No one is suggesting making data wholly inaccessible.

Data that you cannot access “at any time and in any circumstances” (author’s words) can still be secure. A fairer analogy would have been storing disks in a locked safe in your home. It’s not as convenient to access it, but it is secure. Should you do that for all your data? No, but neither have I advocated for that. I very clearly stated that I think it’s OK to have different levels of protection for different types of data.