The argument
isn't that some games are not possible on last gen consoles at the start of a new gen, the argument is that a game(especially one 2 years in) without constraints of the older platform allows for a much bigger and fully realized game. Some people are erroneously reading into this as saying the Series X or PS5 version of a game will "suffer" in terms of performance or visuals and that's
not what I'm saying.
Right at launch a game like Killzone Shadowfall or Infamous Second Son looked and felt markedly ahead of games similar to them which were cross gen or last gen.
Second Son had a much richer and more detailed open world with much more interactivity and things going on it than say MGSV which came out a year
later than Infamous and was cross gen. It didn't simply look like Infamous 2 with better graphics.
Compare a game like Infamous Second Son or Batman Arkham Knight(2014/2015 game) to MGSV(A 2015 game but cross gen)
Compared to cross gen MGSV
MGSV's open world was very bare bones and outside of enemy base camps it was barren and desolate. The current gen versions were "better" by way of 60fps and had better IQ but the fundamental game design was the same. That's the point. Of course to some they'll say it being 60fps is a case of the game not being held back but it's not about the performance/image quality but the game itself but since a version without constraints doesn't exist you can't really find an equal comparison.
The jump between this gen and next gen is even bigger especially with the SSD. Nobody has said how a game that's designed to take advantage of an SSD constraint free will somehow run just fine on a 5400RPM mechanical hard drive. Not to mention the massive difference between the Jaguar CPU in the PS4 and the Zen 2 architecture PS5 CPUs.
Just like on PC now, having an PCI-E SSD offers basic improvements(faster loading times) but nothing ground breaking which developers have spoken about since the new consoles were revealed. The fast speeds of the SSD right now on PC doesn't change the game as the games wasn't built for it.
Killzone Shadowfall looked way better than any 2013 PS3 exclusive too. Shadowfall looked way better than a game like TLOU on PS3.
Tl;dr native games built for a new console>>>>>cross gen games. Can't believe something as simple as this is riling people up.