Responses

It's a cultural thing
Elders are looked at with the utmost respect
And parents are seen as someone you must be obedient too
To call someone "father" or "grandfather" would be basically bowing down to that person and submitting to them
There's a bit more too it than that but that's the basics of it (=・ω・=)
Yo what's is everyone's obsession with wanting to be called dad or calling other people dad