For entities in the heavens above the level of "Great Golden Immortal," entering a secular plane results in the accumulation of worldly karmic debt. A mild consequence is stunted cultivation progress; a severe one is that their cultivation comes to a permanent standstill.
This is why many beings above the "Great Golden Immortal" level, despite being deeply concerned for their descendants in the secular planes, lack the courage to return. They dare not even leave behind a peerless immortal treasure or a technique from the heavens for their kin.
However, for certain powerful factions within the heavens, this restriction is essentially meaningless.
Chapter 2422