Are you claiming there are no crash bugs in those other browsers? I can crash Chrome tabs just by creating lots of HTML 5 audio elements in a loop. And I'm sure there's more.
Of course not - but the crash bugs should ideally be isolated (like your Chrome crash doesn't impact other tabs), short-lived (this bug has been around since mid-2009), and not impact the operating system (only cure for the crashie8 glitch requires loading taskmgr).
I just tried navigating to crashie8.com on IE9 RC, and while it crashed the tab (and one of the other tabs that shared the same process), nothing happened to the main IE window. The isolation seemed to work alright. Did you try this with the beta or the RC?