The pop up I received before logging in at CFC not only contained the "accept" button, but also the message, that by continuing to use this site, I am consenting to the use of cookies of these - not wanted - "services". My suspicion was, that even to log in at CFC by these "services" is seen as such a further use of the CFC site because: Why were additional cookies by three websites be added to my browser, so all should still be available without these cookies for logging in at CFC ? I only deleted cookies set in the last 24 hours and not the existing older ones.
This is confusing in Chrome, it took me a while to figure out.
The short version: There are NOT 3 additional cookies set. At this point 3 sides have attempted to set cookies, but could not, due to you not consenting to it.
Picture #1, cookies from CFC:
This shows a clean Chromium browser, CFC has been loaded, and I have rejected the cookies from the main popup.
On this screen you can see civfanatics (where the arrow is coming from) is setting a range of cookies on the right, 18 in total, if I counted this right.
These are cookies only used from CFC itself, not from the advertisers, and this is the stuff which is necessary to have you logged in.
Picture 2: No cookies:
On the left, where the arrow is coming from, you see 3 more entries, 2 from googlesyndication.com, one from privacy-mgmt.com (the cookie popup). These sites have attempted, or wanted to set cookies. As you can see on the right, in the red square, no cookies were set, since nothing is displayed there.
(the label in the picture should probably not read "visited sites", but rather "loaded sites", or something similar; sorry for the confusing captioning)
#3 picture 3, the difference to actual advertisers:
This is an example if you agree to the advertising. As you can see on the left, the list of sites setting cookies or wanting to set cookies (I'm not 100% certain about that) is a lot longer, and on the right you see that they actually do set cookies.
Short version again:
If you do not consent to cookies being set, then no cookies are set.
To use CFC only CFC cookies are necessary, and these are not used for advertising. You do not need to agree to advertising cookies, you can use CFC without them.