What is nice about the Unreal Editor is the number of items that are included within (walls, windows, cars, scenery, and so on). I have not counted them all, but I would guess that there are a couple thousand unique objects. Yet there are still a lot of common objects that are missing.
While it would most likely be easier to find said object on the internet and import it into the editor, I have always tried to create whatever I needed using the objects in the editor. It is always interesting to see what the final product used.
I think of it like Legos. One could always make there own Lego if they can not find the right piece, but it is almost always more satisfying to work with the pieces available to create the final product.