Why Bricksforge timelines need a trigger?

Building some animations today was asking myself: why bricksforge gsap timelines need always a trigger?
It is obvious for scrolltrigger ones to have a trigger but for normal timelines generally you don’t use a trigger:

Or am I missing something obvious? Normally this isen’t absolutely a problem, it can be in some edge case:

  • for example if you want to animate elements that are not in the same page: sycronize header with offcanvas, page transition ones , preloader just to give the idea.