These are legit concerns, but they will never win the argument. Yes the example given is the problem with DRM, but it is so specific that there will be no mass uprising to protect it. And having DRM built in does scare me. Imagine not being able to take a screenshot of something on a webpage, or being prevented from copying text from an article. All of this could be done with DRM.
That being said I am hoping we have enough of an open browser system now to avoid the chokepoint issue. There are several open rendering engines that browsers can use, so there will always be an alternative to the IE problem. Those browsers can support DRM while still insuring the rest of the web stays open. In a way I think the market will show that DRM taking over the web won't work. It's tolerated on videos because everyone came to the same conclusion as Tim.