If they don't realize what it actually is. There are a fair number of people out there who don't want to use another browser because it's confusing to them, or

If they don't realize what it actually is. There are a fair number of people out there who don't want to use another browser because it's confusing to them, or they like IE. A website could just put a big "Speed up this application" button that installs the Chrome Frame plugin, and as far as the end-user is concerned, it's just like installing Flash - and they're still "using" internet explorer. The target audience for this is not the people who are interested in Chrome; it's the people who aren't interested in moving away from IE.