Incognito mode is such a terrible choice of name for this feature, and Firefox's "private browsing" name is almost as bad.
To the average non-techie user, 'incognito' implies being anonymous. And when you go anonymous then nothing you do is linked to your real identity, right?
Wrong.
In real-world analogy terms, it's more like using a pen-name as an author. Members of the public might not know the person behind the mask, but your publisher (ISP) and your agent (Google) certainly do.
Pretty obvious why people would get the wrong idea.
As a developer, my primary use-case for incognito is a new session to test a site with clean state, or - in absolutely dire circumstances - to cheat at Wordle.