Very simple:
“Pages” are the default post given when we install WP.
If a ‘Page’ is created with the Bricks Editor, it should be rendered that way.
If I create a Template with a display condition for “All Pages”, it should only use this template is Bricks Editor is not used for that page.
There are plenty of ways this could be implemented, without using default fallback behaviour as I have outlined above. Such as giving some new options in the display Conditions… like maybe an option that is “No Bricks Content Available”.
But currently, it seems there are only workarounds to achieve this. As noted by others, this was a popular feature in Oxygen. I relied on it all the time.