Xbox One Why can't I play games from hdd without inserting disc?

[Dave]

Hi. I'm new to this forum and xbox one. I have 2 hard drives but always have to insert a disc to play.

Xbox 1 500GB
1 1 TB HDD
1 3 TB HDD

Why can't I just store them and then pull them up when I want and just play without inserting disc?

Thanks for any help,

Dave