You will never have a UI capable of encompassing all the settings available in Linux. You will only have a UI capable of configuring your desktop experience, which is just a small subset of the full Linux experience.
Is it unreasonable to ask "why not"? I like the state of Android's (as packaged by GrapheneOS) settings UI much better than any other settings system, period.
It's all in one place - I can't think of a single thing I would want to configure that isn't found in that one dialog. It doesn't always make sense, but it's searchable, and the search works.
You will never have a UI capable of encompassing all the settings available in Linux. You will only have a UI capable of configuring your desktop experience, which is just a small subset of the full Linux experience.