I think calling CONFIG.SYS a hidden file is a bit harsh - 99% of MS-DOS users back in the day would have known about it, and the AUTOEXEC.BAT file. People used

I think calling CONFIG.SYS a hidden file is a bit harsh - 99% of MS-DOS users back in the day would have known about it, and the AUTOEXEC.BAT file. People used MENU, and similar, to build up different config files and device-drive setups for launching different applications. Even into the early Windows days people would still tweak their config.sys files.