Can't speak for others but I do not enable it because doing so could lead to me being tracked as the majority has it disabled. This is also the reason that the tor browser also has it disabled.
I am not aware of any popular browsers that enable it by default in this day and age.
> On April 3, 2015, Microsoft announced that as of Windows 10, it would comply with the specification and no longer enable Do Not Track as part of the operating system's "Express" default settings, but that the company will "provide customers with clear information on how to turn this feature on in the browser settings should they wish to do so".
So for the specific browsers that do follow the standard, like Edge, Chrome, and Firefox, why doesn't Google respect the flag for those browsers now? I know that Google has the ability to detect which browser I'm using, because they tell me to install Chrome every time I visit their homepage.
I'm seeing IE mentioned all over the place here, but it what it looks like is that one bad actor was just the excuse the advertising industry needed to mass-ignore the setting on every browser, everywhere, regardless of whether or not they violated the standard.
Edit: internet explorer used to do that (https://en.wikipedia.org/wiki/Do_Not_Track#Internet_Explorer...)