Huge chunks of the Internet will be effectively unreachable, and which sites go into the censorship bucket will be decided upon in secret, by unelected employees of big corporations, like China's Huawei. Sure, you can untick the box if you want, but as David Cameron's advisors will tell you, defaults are powerful and most users never change them.
"The type of tracking, called canvas fingerprinting, works by instructing the visitor's web browser to draw a hidden image, and was first documented in a upcoming paper by researchers at Princeton University and KU Leuven University in Belgium. Because each computer draws the image slightly differently, the images can be used to assign each user's device a number that uniquely identifies it."