Before we dive into my take, I recommend watching TechAltar's take on this.
However, for completion, here's the TL:DR:
And, as a custom ROM flash-happy person, here's my additional points:
Let's dig them 1 by 1, shall we?
Stable TWRP for A10 isn't available yet : Link
And, with Pie / Oreo TWRP, while A10 ROMs can be flashed & used from there, TWRP may not be able to mount /system as it normally would.
Obvious example for AOSP-based: LineageOS & LiquidRemix.
With a minimalist OS like Lineage, the settings are mostly stock, save for some additions, such as:
In contrast, a heavyweight OS like LiquidRemix would have their customizations settings like:
And, that's just AOSP-based custom ROMs. Stock ROM from Samsung / Huawei introduce lots of modifications, so much that their UI is far removed from AOSP. In addition, Huawei's EMUI forces the user to use the stock launcher.
Will test for now.