SE has been like this even with XI.
You still get a number to work with, your stats and your potency. The understanding they want the player to have is as they go up, effectiveness will as well. Essentially this much is true.
The underlying formulas they don't want you to know. It keeps it somewhat mysterious and also will allow them the ability to change things under the hood as needed for balancing without directly changing potency values.

They've made overall battle damage calculation changes before multiple times and never once mentioned it in any patch notes. The only way you'd even know is if you knew what to look for.