Ranger D for Giants

Can Giants become Rangers? Although they can't wield a bow, Throwing Attack is technically a ranged ability and only Rangers get Crit training.

Yes, they can. Also, choosing a beginner destiny as one also works. However, this helps them in no way. Throwing attack is only in the melee destiny.

You're implying that Dex has little use for Giants, am I right?

o.o other than life skills (if a giant does decide to go that path) and balance on weapons, not really no. But They can benefit from any destiny really. Trying to get ranger destiny on my giant for crit training (she's in limbo :c)