I think developers and adobe users that use multiple Adobe Applications will develop a love affair with Libraries for creative sync copies object into the libraries in a form that will be usable by all Adobe application and these can be shared with others one work with. Adobe added SVG support into libraries so things can be dragged form a library into application like Photoshop and come into Photoshop as vectors.
I only use Photoshop and I keep libraries in the back of my mind but so far hand not found a real reason to use them. I know I can now install and use products like Indesign and AI. However it took me too many years to learn Photoshop well. Now its my adult toy. While some of the new vector shaper tools Adobe demo they added to AI look amazing. I wish they would also add such a tool to Photoshop. I'll be 75 in December and this old dog just dosen't want to use a mountain of time learning all the creative clouds applications. I believe I could learn to use them but the time needed to learn them would be a poor investment IMO.