Srila Prabhupada explains that the Lord deputes some of His devotees to remodel the fallen condition of human society:

“…When there are too many asuras in the world, then it becomes a hell for those who are devotees of the Lord. Due to the growth of the asuras, the mass of people who are generally devoted to the Lord by nature and the pure devotees of the Lord, including the demigods in higher planets, pray to the Lord for relief, and the Lord either descends personally from His abode or deputes some of His devotees to remodel the fallen condition of human society, or even animal society. Such disruptions take place not only in human society but also among animals, birds or other living beings, including the demigods in the higher planets…”
[Srimad-Bhagavatam 1.13.50]