You know those adverts that track you from one site to another so if your on the Northern Territory News (for all your crocodile related news) it shows adverts from other sites you have been on earlier. I sometimes feel stalked by new relic offers for example.
The aim of DNT is to avoid that slightly sinister feeling behavior and avoid advertising and other networks tracking you across sites. This does seem on the verge of being evil and just as you can opt out of marketing emails surely you should be able to opt out of this kind of tracking.
Be nice sometimes if customers were more aware of DNT, see more details here, seems in outline a good idea. But depends on web developers and more complicatedly advertising networks honouring it. At the moment its a bit of a request please opt me out of third party tracking which may or may not fall on deaf ears.
You can disable third party cookies depending on your browser but that may lead to some issues under some sites. For example on Firefox this is how here.
So at the moment I’m redirecting a bunch of sites to a local site on my laptop via the hosts file. Which cuts out a whole bunch of rubbish but its not really for the amateur. This also speeds up some sites for me which are quite slow with big old flash adverts.
Its a bit of a nuclear option though as once you have set it up you can’t see anything from that site even if you wanted to.
So the best solution out there for a normal person is still probably an ad blocking addon for your browser although again its not really solving the issue of tracking, more blocking the result.
Perhaps DNT will get wider adoption as it gets more standardised but i guess because it makes people money they have little incentive, but then that was the same a few years ago for popups and they are now radically reduced.
You can see your browsers DNT preference here. Which also shows instructions on how to set it in some browsers.