Khtml/Webkit used the opposite model and won big.
Funny enough though, Mozilla's insistence on JS as general-purpose was likely a factor in the long-term survival of what was, back in the days, a wobbly and improvised browser-only scripting language. In many ways, you could not have had Node without the XUL years; but the JS explosion happened on Webkit components, (fatally ?) wounding the Mozilla platform. History is funny like that.