IIRC the yeast becomes accustomed to sucrose and will shut down before it starts munching on maltose in the final beer.
That claim is homebrewing myth. Dry yeast is propagated using a fortified molasses-based medium that is composed mostly of the disaccharide sucrose and the monosaccharides glucose and fructose. The ability to transcribe enzymes that break the glycosidic bonds that hold sugars more complex than monosaccharides together is part of a yeast cell's genome (see
http://www.experimentalbrew.com/blogs/saccharomyces/carbon-credits) .
Table sugar can be used as a carbon source, but it has to be fortified with a vitamins, minerals, and a source of nitrogen. However, it is not something that I recommend to a new brewer. DME is the most foolproof medium for the new brewer.
Unsulphured blackstrap molasses that is fortified with diammonium sulfate (a source of nitrogen) at a rate of 1/4 teaspoon per liter can be used in a pinch. Blackstrap molasses is what is left over from the refining process; therefore, it contains all of the trace elements and vitamins that were in the original sugar source before it was refined.