It doesn't really mean that, no. You don't need to know any CSS, HTML or DOM to get started in Cappuccino. If we've done our jobs right, you'll never need those things unless you're doing seriously advanced hacking (and even then, only in rare circumstances).
Sproutcore, on the other hand, really does need you to be an expert in all of those technologies, plus its own, plus ruby helpers to actually put anything on the screen.
I guess I should be a little clearer. I am already an "expert" in CSS/JS/DOM/... (after spending years doing web stuff and then over a year as lead dev on Flock). I really like the languages.
I've not used Obj-J so I cannot say if I will like it as much as I like JS. The idea of cappuccino providing a cocoa for the web is great, I just wonder if it could have been done without requiring a "new" langauge
I look forward to experimenting with your framework though.
Objective-J is actually a fairly thin layer on top of JavaScript. It adds classical inheritance to JavaScript, not unlike what most JavaScript libraries try to do, except it cleans it up (IMO) with Objective-C style syntax.
Even SproutCore is resorts to preprocessing code to get syntax enhancements, like their sc_super(whatever) which is converted to arguments.callee.base(this, whatever).
Sproutcore, on the other hand, really does need you to be an expert in all of those technologies, plus its own, plus ruby helpers to actually put anything on the screen.