@Tuco Allegedly? Where are you hearing this from?
I'm genuinely curious, because it seems odd to tease bard, paladin, and sorcerer but not the barbarian, druid, and monk.
https://baldursgate3.wiki.fextralife.com/ClassesMentions that:
Not all Classes will be available at the start of early access, but all classes will be in the game at launch of the full game. Multiclassing is not available on release of the early access version.