The only difference is, developers care about fixing their games' bugs and glitches. Bethesda doesn't give a shit. 5 years later a new 'remastered' Skyrim released, and what do we get? Same bugs and glitches with graphics out of late PS3/XBOX360 generation.
It is never about the engine; a competent developer can make wonders even with GameBryo (one of the worst 3D engines so far, and bethesda use a modified version of this called Creation Engine, by the way).
7-11 FPS difference is what I would call bullshit. RTX 2080 Ti is at least 29% better than GTX 1080 Ti by most benchmarks. Add DLSS and that gap will be even larger.
The problem with Xbox is that Microsoft doesn't have much faith in its product. That's why Microsoft didn't pour much money in to its gaming division. Spencer is trying to change that, and I think he succeeded to an extent giving how Microsoft has put much more money in its gaming division over the past few years. If he actually manages to change that mentality, all power to him.
I have exactly 158 games in my backlog, and I just keep adding to them (because of sales, damn them) while being unable to play due to lack of enough time.