It's a perfectly fair point. The fact that the largest Chrome task by far is not a tab or extension at all, but is the core of Chrome itself, indicates that maybe - just maybe - Chrome isn't doing as good a job of keeping things isolated as it should. That process shouldn't be doing a whole lot beyond driving the UI and managing the lifecycles of its children.
The point is to isolate any code which renders HTML, plugins, etc., i.e., anything which processes untrusted external input, something which the main process does not do.
