That's a bit overstated.  It's quite possible that a GUI editor could be
a helpful tool despite its limitations, but there are limitations.  Most
significantly, Java is designed for graphical interfaces to be describe
logically, rather than by pixels.  It's only when you want to place
controls with exact numbers of pixels that a GUI editor becomes a must.  
For example, that's why it's difficult to get by without the things in
Microsoft development environments.  When you want to place controls
logically, a description in code is often as easy to create as a GUI in
an editor.

That doesn't mean I don't think such tools can be useful, but I do think
that they often create a desire to use pixel placement of controls from
people who ought to know better.  The ones I've seen are very poor at
making it apparent that you're working with a dynamic, moving, resizing,
adjustable user interface, and not just a picture.