Baldur's Gate Enhanced Edition

[Kish]

...to dual-class. And between Baldur's Gate 1 and Baldur's Gate 2, the number of dual-classed characters is three (3): Imoen, who is the main NPC, Nalia, who has the same Intelligence and Dexterity as Imoen, and Anomen, who does not in fact meet the Wisdom requirements for his dual-class.

So no. That is not why almost all the characters in the Baldur's Gate games have very high stats.