It depends if you look on startingpoint as "just make your own image if you don't like main, bluefin or bazzite" or you look at it like "a way to standardize all Ublue images".
I agree that it is easier to just use an image if your modifications are closer to it, as it gets rid of maintainance burden.
That is true & I agree. It will be good to document that "if you are using startingpoint, you should know that you are a maintainer now, so it is your worry on how end-user experience will be".
But, I would say that making & maintaining startingpoint image is far easier than forking regular ones, so you will have less maintainance burden. I would argue that forks on Containerfile-based images would die faster.
It is true that there are more merge conflicts if you are not following the standards of starting-point. Containerfile is better if you want to be creative & to break the rules. However, if you think that something should be handled better, make an issue where we can discuss why "rules had to be broken".
This one I don't understand. What is hardware-setup & image-info in this context? I know hardware-setup service which exists on Bluefin & Bazzite. Am I thinking in wrong direction?