2. That's not a good analogy. If we're looking at a single choice in isolation, it's true that opting into DNT (or RFP) makes you stick out compared to everyone. There's only two options (DNT header being present or not), and one option is obviously more common than the other. However, the difference with RFP on/off is that there aren't really two options. Yes, RFP can only be on/off, and "on" is much more rare than "off", but leaving it "off" also uniquely identifies your device through fingerprinting. You're not really choosing to blend into the "all the people with RFP on" group vs "all the people with RFP off" group. You're choosing to blend into the "all the people with RFP on" group vs "all the people with RFP off and has the fingerprint as you" group[1]. Whether that's more or less identifiable is unclear. If you have the most run of the mill setup[2], then RFP might indeed make you stick out more compared to your normal setup. However, if you have an uncommon setup, it might make you stick out less, because the amount of RFP users is greater than the amount of users with the same fingerprinting attributes as you.
[1] in reality it's not really one group for RFP users and separate groups for everyone else. There are fingerprinting attributes that RFP doesn't block, so it's more like a set of groups for RFP users, and a separate set of groups for non-RFP users, but there are less distinct elements in the RFP set, since various fingerprinting attributes are spoofed to be the same.
[2] see https://wiki.mozilla.org/Security/Fingerprinting for list of features that are spoofed, and make your own determination how common your setup is.
> So in short: your normal browser does not have to be honest about it's properties, but it won't make you more anonymous because you still stand out from the other people and content on the web will break. Tor works because everyone has the same properties, including resolution. You can surely change your resolution, but there is just simply a chance that you will be standing out from other people. It's just safer to keep it the way it is.
If the "resist fingerprinting" feature changes anything in the data that is read by trackers, you will stand out like a sore thumb among the millions of browsers with the default settings.
Most people do not change default options, so just turning on that option is something that identifies you.
To my knowledge, resistFingerprinting mostly does the latter.