I'm guessing you're thinking 7, sans the X as X7 was a PS2 game. Off the top of my head, I'd guess it would be a matter of cost and possibly convention.
You wouldn't spend the money on the requisite cartridge save hardware unless you had to.
At the time those 128KB PS1 memory cards were a revelation and quite expensive. Games in the cartridge era generally used battery-backed saves.
You wouldn't spend the money on the requisite cartridge save hardware unless you had to.
At the time those 128KB PS1 memory cards were a revelation and quite expensive. Games in the cartridge era generally used battery-backed saves.