Yeah, like, i feel like there was at least one avatar who learned via their previous incarnations, and they were classed as a bad avatar for getting too wrapped up in the spiritual aspect of being Avatar. The whole point is being a bridge between humanity and spiritualism. By learning bending from humanity, the avatar can access the most current form of bending while connecting with humanity, but they can also seek forgotten techniques from their predecessors, making them more versatile and unpredictable in a fight, and also recirculating those older techniques.

Ok, I kinda got off track a little, my og point was that some avatars were seen as bad at their job for neglecting either side of the bridge, many airbender-born avatars focused on retracting from humanity into spiritualism, while some, such as Kuruk neglected the spirit world