It's an odd but true little fact that I just learned. Apparently it's a legacy from the first days of version 4.0 when JavaScript Style Sheets (JSSS) were being considered as possibile alternative to CSS as we know it today. At that time Netscape married CSS to JavaScript, and never divorced them until version 6.0.
So, if JavaScript is turned off, Netscape 4.x will not render any CSS styles at all. Now THAT'S a kick in the rubber parts!