Um RIOT? Maybe you need to RE-LOOK OLAF for a sec.

Ya olaf is flawed he's just Volibear, but nerfed version of Volibear. He moves so slow and his axe throw isn't reliable enough to catch down opponents and he has no escape so he gets kited so easily. Volibear's q is just more useful/reliable, as an escape and catching down opponents. Volibear's bite also do A LOT more damage than olaf's true damage E. At lvl 18 for example, Voli's bite can do well over 600 damage. While olaf's e does true damage, its only about 300. VOlibear's ult gives 75 damage at lvl 1 and lasts 12 sec plus its AOE magic damage, while olaf's ult at lvl 1 gives 40 physical damage and only lasts 6 seconds. And Despite olaf's decent lifesteal, volibears passive overall makes him more tanky.

So all in all, volibear is better than olaf as a dualist and more useful/reliable/tankier in team fights. Don't get me wrong, Olaf is a not a bad dualist, just that Volibear is a better dualist. If you think I'm wrong, please don't hesitate to enlighten me on why he's not inferior to Volibear.