DO_NOT_TRACK is forever tainted by it's initial Microsoft introduction and the massive opposition of the tech community at the time to this idea. Apache webserver to this day strips the DNT header in it's default config.
Accepting DNT would imply that the tech community was wrong on this one, and that will never happen.
No, the real reason is because it's trying to use an optional technical flag to enforce a social/political policy, and as such was doomed to failure from the start. If I recall correctly, the "tech community" was largely in favour of DNT, and anti-advertising in any case. The advertising industry, however, was not, so why bother implementing something that goes against their own interests?
The only workable solution to that problem in practice is legal/political: legislation and sufficient regulatory abilities to effect compliance (i.e. GDPR/PECR and the like). In the end, the US stuck with permit-all-by-default and largely don't care, the EU/UK went deny-tracking-by-default with penalties to back it up.
The reality is that this proposal will fail for much the same reasons: either you have an opt-in mindset from personal beliefs or legal requirements, in which case the global off-switch is worthless to you; or you're pro-tracking, in which case the incentives are to ignore the switch. Or you're Debian etc. and you remove the tracking code outright...
Accepting DNT would imply that the tech community was wrong on this one, and that will never happen.
So it's dead without a name change.