Sugars are fairly simple compounds, but immediately become more complicated when they are examined. Some sugars are fermented readily, others less so, some not at all. Honey is a more complex substance yet, although mostly sugar. Malted grain is FAR more complex than just the sugars derived from it (thank God!), and it is all these complexities that give us such glorious variety in beers, including ales, lagers, lambics, etc. as well as other base stocks with their own complexities that produce fermented beverages like mead, cider, and wine. Sugars are required for the anærobic fermentation that produces the alcohol and CO2, but there's far, far more to this pastime than that.....otherwise we'd all be drinking some fairly uniform swill (probably tasting a lot like a BMC Light beer), and enjoying it not much at all.
“Malt does more than Milton can / To justify God’s ways to man”
-A. E. Housman (1859–1936). A Shropshire Lad , 1896.