It's running JavaScript apps which brings up a lot of these issues. Read a little about the history of Firefox and it's memory management and security issues and you can see why they built Chrome. Chrome can gracefully handle a buggy JavaScript application without failing vs. the Firefox issue of one tab locking all of the rest of them. etc.

PS: I don't think browsers are a true kernel but they are getting a lot closer. I am going to wait a few months for chrome to work the major bugs out and then try it.