this is the declaration
As of today, web browser Do Not Track settings will no longer be enabled on Yahoo. As the first major tech company to implement Do Not Track, we’ve been at the heart of conversations surrounding how to develop the most user-friendly standard. However, we have yet to see a single standard emerge that is effective, easy to use and has been adopted by the broader tech industry.
it means in fact that the initiative of great big noble intentions is now being send to the dustbin as silently as possible and with a lot of whitewash and seflpromotion
they don't do that to give a personalised experience, with do-not-track you could personalise your experience as much as wanted or not - that is effectivly personalised
you will now have to use proxies, tor and other tools to stop the cookies, webbugs and other indicators that will try to follow your login (use different for different services), your browser (you can change), your IP address (use a proxy for that kind of service that you want to seperate from the global dataview)
it shows another time that the big money is in profiling and that profiliing brings only money in if they are capable of collecting even the most detailed information of you. It shows that Yahoo is out to make more money and that they will do anything that is necessary to do that. To put it bluntly they are datawhores, selling data like whores sells their body, only they are selling our data (and we had to give permission)
you can opt out of their profiling program here https://info.yahoo.com/privacy/us/yahoo/opt_out/targeting/details.html but that is only minimal