I am unsure of where to post this but I am assuming this is a decision made by the team to not allow your 1 action bar be visible. It would be nice to have that as an option to hide it.
You can do it if you download bartender.
Not sure why you wouldn’t want any action bars at all, but you do you.
Anything Blizz can do addons do better; addons do interface better than Blizz. 