Ars Technica:

Yahoo yesterday announced that it will stop complying with Do Not Track signals that Web browsers send on behalf of users who wish to not be monitored for advertising purposes.

“As of today, web browser Do Not Track settings will no longer be enabled on Yahoo,” a company blog said. “As the first major tech company to implement Do Not Track, we’ve been at the heart of conversations surrounding how to develop the most user-friendly standard. However, we have yet to see a single standard emerge that is effective, easy to use and has been adopted by the broader tech industry.”

As one of the commenters pointed out, “this is in a nutshell why optional compliance doesn’t work.”