What they're saying is that it should be the user's choice, not the developer's. If I want to run your gallery app with only a handful of the pictures that I have, I should be able to do so.

Because ultimately, developers don't really need to care. Too many users don't understand the implications at all. And if it's for example a messenger that all your friends use, you don't really have much of a choice than to trust it, if you want to talk to your friends.