Feedback Open prefab button in inspector

I think this button only slows down the workflow. If I click on the prefab, isn't obvious that I want to edit it?
What is the functionality of this button?

Edit: I'm currently using Unity 2018.3.3f1

 

double click opens the prefab.
you can single click on a prefab (or any asset) because:
- you may want to see the preview
- you may have some scripted action (

[MenuItem]

) that operates on

Selection.activeObject

- you may want to multi-select a couple of them and drag them in the scene, or execute some scripted actions
- etc...