Shinso may have been the trigger for him to communicate with them, but it seems as though the original OFA is doing something due to the contact with his brother. It seems like the power needed to basically "charge" up. It's as that one successor said, OFA just got more powerful the more successors it had. So Deku basically got the original power x6
maybe bloodline maybe he has a blood connection with first wielder somehow or maybe because of selfless hearth? yeah i know the other wielders are legend anhd definitely good people too but maybe deku is more selfless than them like first wielder because i cant think something else
Deku must have something special from all the previous One for all user, so that OFA chose him to manifest all the previous quirks .
And being quirkless is not the thing
So what is it, I wonder ( ̄へ ̄)