Well, according to "the world's top beer writer" Roger Protz, writing in the latest issue of What's Brewing it isn't.
Oh yes it is, according to anyone who's ever brewed with it.
For those of you that don't know what I'm wittering on about Crystal malt is a type of malt used in brewing that has been stewed and caramelised before it gets to the brewery. This does, as Roger Protz says, give colour and caramel flavour to finished beer. It does not mean it has no fermentable material though.
According to the excellent Murphy & Sons website Crystal malt has 275 litre degrees per kg of fermentable extract, compared to Pale malt with 305. You don't need to understand what litre degrees per kg means to see that though Crystal malt has less fermentable material it's certainly not devoid of it.
You really need to have made beer before you can start to understand it.