The PS5/new XBox are targeting a ~5 year generation. This means that games will be mostly playable as long as you get a top of the line 14nm GPU for 5 more years.
Remember that graphics have stopped being a bottle neck for games for a few years now. The top played games: Fortnite, Apex, LoL, Dota, Fifa and the like are perfectly playable on mediocre graphics.
But you had me going for a second. Nethack is also turn-based, so there's no real-time element at all. If you come across a difficult turn, its a common "strategy" to walk away from the computer, relax a bit, and then look at the screen with a different mindset. Maybe you can think of a better solution if you give yourself time.
(Although I assume nethack is more clever than just "re-send the whole screen for every change".)
No one said anything about the data changing ...
(and yeah, I believe it only sent data for the delta.)