Why do I need to have all my Photoshop Libraries physically on my hard disk?

Why do I need to have all my Libraries items physically on my hard disk?

Why can't I have just a preview of them and if necessary download the item?

Let me explain. I work at a company with over 100 designers. We have thousands of items in Photoshop Libraries. Sometimes I need to use one of these items. But I don't understand the need to have around 40GB on my hard disk if everything is also in the cloud.

For comparison, if I have Google Drive installed on my computer, it won't download all the files I have on my Online G-Drive. Just what I 

For comparison, if I have Google Drive installed on my computer, it won't download all the files I have on my G-Drive Online. Just what I ask.