@LukeAlmighty @HumongusChungus nah, it really is the power. The ps3's hardware is fucky so trying to emulate it is really difficult. Putting the cell processor into the ps4 would have made it cost more too, and that's not good when companies already sell consoles at a loss. Heck, amateur hobbyists have only barely been able to get ps2 games running on non-BC PS3, with some issues, because of the emotion engine.
It was much easier for Sony to add ps4 compatibility to the ps5 because they're both just x86. They could have probably added ps1/2/3 emulation to it though. That's where it gets scummy.