Internet Explorer's market share was a little more to a little less than Chrome's in mid 2012. It was the only significant browser to enable Do Not Track by default as far as I know.
Advertisers wouldn't have cared until laws forced them to care. Microsoft enabling it by default ensured there would be no laws.
You are right, my memory was off by a few years. In 2012 Chrome first overtook IE, in 2014 Safari overtook them, in 2015 they crossed 10% and by the end of 2016 dropped under 5%.
Microsoft's final gift to advertisers before dropping of into obscurity.
