Xbox One has about 5GB DDR3 RAM available for games and a 2013 GPU. The hardware is pretty much as old as the GameCube was when the Wii launched.
To give an example of how far behind the Xbox One is in terms of specs compared to modern machines.
I'm pretty sure the Xbox One X could handle more but Microsoft and Sony have set the rule that everything needs to run on both PS4/Xbox One as well as PS4 Pro/Xbox One X.
Had Anthem been a PS4 Pro/Xbox One X/PC only game it would've probably turned out better.
In fact some early 2017 Xbox One X demo material (like Anthem) show signs that this 'rule' wasn't there from the beginning and that demo's like Anthem were made with just Xbox One X specs in mind.
(remember that at some point Microsoft considered to not do an 'Xbox One X' upgrade type thing but launch it as a 'next gen' console instead)
Also don't underestimate the additional resources required for optimizing online play both on fast wired internet connections as well as wifi.
As for the 'scope' not changing. I don't agree with that at all. Online play on Xbox 360 was mostly limited to small maps. Open world games with online play weren't that common either.
I recently looked back at some Xbox 360 games and some really don't hold up anymore.
Anthem seems like something that should've been kept for next gen. A killer launch title and BioWare would've had the time they needed to get it perfect(like they had with the original Mass Effect) plus it wouldn't have been limited by the current gen hardware.
Open world games with online play were not that common, but they did exist. GTA online and red Dead Online existed. What other open world games with online are there even that people play? Are you counting things like destiny, which released on ps3 and 360
I think most of the deficit in online play last gen was really because very few games used dedicated servers. One of the few series I can think of that has a clearly gimped online on 360 was the battlefield series, which never had the 64 player online afaik. But I also think it never had dedicated servers until this gen.
Certainly, not every game can be simply ported to last gen, but I just haven’t played anything this generation where I said “wow this was truly not possible before”. I’m not really talking about graphics, as those are obviously better but just the idea of “is there anything in this game that fundamentally could not be realized last gen?”
Even the the big games like Red Dead 2. Sure the world might be too big and detailed for a dvd, but fundamentally a very similar experience could be had last gen. This is just different to previous generations st least from my perspective. When I play some 360 games, there’s a lot of them that imo just couldn’t really be done justice on a PS2. GTA5 or Red Dead Redemption just would be fundamentally different games on a GameCube.
In fact, I would say that the most fundamentally unique game in scope I have played in the last few years was basically on last gen hardware. That would be Zelda.