You’re right - they do expect that. Regardless of the availability of information, and I agree there is a wealth of it available, companies should work a little harder on explaining this. It’s a new problem for most people.

When the batteries in a remote control, clock, or even a car go bad then it’s trivial to change them. So while this problem has existed for as long as battery powered devices have the difference is that no one noticed. Now you can’t change the battery yourself. So it becomes a much bigger burden to understand “oh, the max ability of my battery to charge has degraded.” It’s just a new piece of knowledge for lots of people.