I've been thinking today, or at least for the half hour I've been up. Microsoft created Active Channels (CDF) back in 1997, before Windows 98 was even released. RSS is just channels with different names, released two years later. So, why did the internet suddenly adopt RSS? Back when RSS started becoming popular as a way to aggregate blog postings and news, something like 99% of the world could have been able to use channels, but instead websites chose RSS, which maybe 1% of the world could use. I did a little googling this morning (mainly to find out when RSS was introduced, 1999), and I can't find a lot about CDF vs. RSS at all. The populizers of RSS knowingly chose a technology basically identical to channels that far, far, far fewer people could take advantage of, and I can think of only one reasonable explanation: RSS wasn't from Microsoft.
(For historical accuracy, I should point out that Microsoft didn't invent the idea of a syndication format. However, they did create the first XML syndication format, and they did offer the first successful commercial product that took advantage of it, Internet Explorer 4.)