Mr incognito is useful to not mix up cookies and logins, in case of soms temporary actions. That's about as useful as I found it.
Discussion
yes. it serves a purpose far more mundane and much less private than the marketing would have you believe. it is much more secure and private to spin up a self-destructing dvm in #qubesOS but alas on mobile #grapheneOS when i reach my article limit or need to test something while logged in, it does the job