[It] could be abused to not only identify protesters at political events and rallies, but to target them for selective jailing and prosecution, stifling their First Amendment rights.
In addition to invading your privacy, these tracking requests can consume large amounts of data. And transferring lots of data takes time. Generally, the more tracking requests on a website, the slower that website loads. That’s why DNT+ gets you surfing at 125% of the normal speed and with 90% of the bandwidth, compared to a browser without DNT+ running.