> Introducing te "do-not-track" header was a great idea but it has been completely ruined by major browsers turning it on by default so the trackers have legitimately chosen to ignore it.

This seems to imply that doNotTrack would have been successful for its intended purpose had it not been a default setting at one point, which feels like wishful thinking.

Sure, that aspect made it impractical for uncharacteristically privacy-minded companies in the space to support the header, but the vast majority of companies in the business of tracking and advertising would have ignored it anyways, because there's zero consequence for not doing so.