Xbox 360 onwards have all been a lot closer to a general purpose PC than the custom hardware consoles used to be. Xboxes run Windows so Xbox games are built to run on Windows on 1 or 2 hardware configurations per generation
Playstations before the 4 were all quirky and all ran their own special weird operating system.
The PS3 used the [Cell processor](https://en.wikipedia.org/wiki/Cell_(processor)) which was an 8 core chip well before its time so all PS3 games had to be made to use wayyy more cores than even PC games had access to. PS2 had a fully custom CPU designed by Sony specifically for running console games
Emulating an Xbox One is easy, its just a computer pretending to be dumber but with no weird quirks to emulate. Emulating a PS3 is hard because you need to emulate all the special hardware in the Cell processor including any weird quirks/mistakes that may have been used as cheats by the game devs. To pull that off you need something significantly more powerful than the Cell processor was
Older playstation emulators do exist, but its not necessarily in Sony’s interest to freely provide and maintain them when they could instead get a cut of remastered/remade games
Latest Answers