Does Logout request always succeed?

I tested Logout request against my own dsp and it always succeeds.
In particular, it returns { success: true }.
This looks weird, as I would expect it to receive session_id at least and it did not complain if it’s missing in headers.

Is there a cookie?

Cookie PHPSESSID=f235350c64bdcd594b00df07f3a439a3

Yes, there is (when in browser).
I’m using API Docs (“Try it out!” button), and I suspect the cookie was set to my admin login account.
However, this action does not get me logged out. I can click this button many times and it always succeeds.
I tried the same via unirest with no cookies and it succeeded as well.