Comment by simias

Maybe it's less common now that tooling and frameworks are more standardized but having spent quite a lot of time messing with the PSX and its emulators I can vouch that it's fairly common to find debugging code and strings in production versions. Simply using an emulator to enable the debug UART will spew quite a lot of debug infos for some games. FFVII has a "debug room" that you can't normally access but is present on retail copies. I also seem to recall that the PC version shipped with full debugging symbols which gave reverse engineers a field day.