It's an inconvenient fact that - perhaps a decade ago - we had DNT, and advertisers were starting to respect it, but then browser makers decided to default it to on, making it pointless.
I'm not sure that was the sole downfall; DNT also had no teeth because it couldn't really be enforced.
I think Microsoft's default-on stance was likely intentional sabotage - Google operates a big ad network and would have to deal with a lot of the fall-out.
However while the ad industry might be okay with a few nerds opting out they weren't okay with most of the general public opting out and so they spread stories like the one you repeated.
There's a lot of money in advertising.
The feasible choices are between (a) DNT, off by default, that the more responsible and regulated side of the ad industry respects or (b) DNT, on by default, that everyone ignores.
Which one is the greater good?
In other words, you're welcome to walk up to me, slap me in the face, and call me a son-of-a-bitch... but that's probably not a great start to a conversation that ends with "Would you please work with me on this?"
And no, I don't want to "work on this", I want to not be tracked by default.
Wow, that's quite some re-framing going on there, if you're casting yourself as the advertiser in that sentence. It's more like if you were regularly "borrowing" my car without permission. Do not track is a bit like the lock on the car, which obviously you can get around in 30 seconds flat. Everyone has a lock on their car, right, and it's installed by default, so by the advertisement industry's reasoning it isn't a true indication of whether I want you "borrowing" it. If you were regularly "borrowing" my car without permission, it'd be reasonable for me to walk up to you, slap you in the face, and call you a SOB, but I'd me more likely to just call the cops.
Data about me is owned by me, and other entities can process it only in strongly limited circumstances. That's the default position, by the standard of basic decency, and also in law. Stop making it sound like me demanding control over my own possessions is unreasonable.
Often it is. Firefox, Brave and Safari explicitly advertise themselves as privacy-friendly browsers.
That leaves non-savvy users who just use whatever defaults exists, but there is an even stronger argument to protect precisely those people - you can't consent to something you don't yet understand.
Tracking can leak extremely sensitive information, just like microphone, screen sharing and webcam permissions could. Protecting the user is a sane default in all of these cases. The fact that personal data has commercial value is secondary, just like it would be with webcam access.
Imo, the only meaningful difference between tracking and camera access is that fully-fledged tracking was an accidental side effect of third-party cookies, and before "we" understood the implications of that a trillion dollar industry was established. The reason we're apathetic to tracking is because it's abstract and novel, whereas snooping to your audio or video is easier to grok.
Instead they exploited the apathy & incompetence of the regulators with their so-called "consent" flow. Considering the GDPR was supposed to be enforced since 2018 and they've made it to 2021 without any consequences I'd say that strategy paid off.