Those who see that happen (Kayteei Chhutti Naal) know only, how this happens. But what I understand and guess, I share.
As we need leaders, teachers, experts in specific fields; so it happens in spiritual realms. As leaders. teachers, experts do favour and help students and patients; so does the GURU.
Guru Sahib on this planet earth, is helping humanity to cross through the BHAVSAGAR, successfully.
Similarly GURSIKHS (those rare ones, Gurbani talks about) also help fellow humanity. As they, rare ones, follow the PATH, shown by GURU SAHIB; others less fortunate, also copy them. They get guidance from them. They serve them. They see them. They associate with them. They respect them. These simple physical activities; ultimately help HOR KAYTEE to get benefited and saved, along with them.
Just remember the Gwalior fort SAKHI of Guru Hargobind Sahib Ji. How the 52 unlucky kings were lucky to get benefited and freed.
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥