"At least Yahoo is honest about why it's ignoring IE10 Do Not Track," noted Mayer, also on Twitter, as he quoted the company's claim that the privacy feature, if turned on, "makes it hard to deliver on our value proposition."
Also on Friday, Microsoft's head counsel, Brad Smith, blogged about DNT. Because his comments were based on an Oct. 23 keynote speech at an international conference of data protection and privacy officials, he did not address Yahoo's move.
In the blog post, Smith defended Microsoft's decision on IE10 and DNT, citing a survey the company commissioned that said 75% percent of U.S. and European consumers wanted DNT switched on by default.
(Smith's Oct. 23 keynote presentation can be found on the Microsoft website ( download PDF).
Smith also urged all browser makers to "clearly communicate to consumers whether the DNT signal is turned on or off, and make it easy for them to change the setting," a reference to Windows 8's notice during setup.
Olds saw Yahoo's statement as giving it an out, noting that the explicit reason it gave was due to the lack of a clear and comprehensive standard, and that the company used the phrase "at this time" in its statement.
He predicted that Yahoo would get more attention, virtually all negative, for ignoring IE10's DNT preference than it had when it announced last March that it would support the standard.
And there will be more tussling, not less, over DNT as time goes by, both Brookman and Olds forecast.
"The most interesting question in all this is how Microsoft responds to companies that reject their DNT instructions," said Brookman. "They can't just sit back and let their users' privacy settings be ignored -- they would lose credibility with their customer base."
"This topic is not going to go away," Olds prognosticated. "As tracking becomes even more sophisticated, it will be a much bigger issue as advertisers use big data along with other information they've gleaned on you. It's going to really start crossing the creepy threshold."
Brookman sees the possibility of a full-fledged war between browser vendors and online advertisers if Microsoft responds by, for instance, blocking ads from domains that don't honor its IE10 signal.