After Effects isn't a video manipulation tool.
Video manipulation is one of its capabilities, it is also capable of motion graphics and animating vector shapes.
This library works off the vector shape side of after effects.
I see what ya mean!
Its always felt like some weird mix of illustrator and photoshop to me.
Strange to how PHOTOshop moved the graphic way and the lightroom became the defacto photo editor.
Guess that's just software evolution for ya :)
It was originally a post processing tool. Hence the name. After Effects.
Which is why this whole thing seems so similar to me.