Earlier quoted context omitted.
I don't know what to say, except that you're right . This is the problem that Tor is trying to solve, which is why Tor gets to claim that it is "anonymous," and random websites or apps don't get to make that claim. I don't think it's a deliberate violation of privacy to operate a website, but I do think that it's a violation to operate a normal website and call it "anonymous." Because, as you point out, it's not. Not…
It's "anonymous" if it doesn't publish your name/identifier alongside your content. 4chan is anonymous. When you use it, you are anonymous to the people reading your comments. Does this app pretend at any point that its operators couldn't identify users if they wanted to? That would be dishonest. But what word do you expect them to use for "your name will not be published" besides "anonymous"?
Where on Whisper's site do they say "this site is anonymous, but it is not safe enough to publish anything with legal implications"? I looked.